maths.bits: fix ambiguous expressions

[lcheylus]

Fix ambiguous expressions for & << >> in vlib/math/bits/bits.v + enable check for math module in vlib/v/checker/infix.v

Without fixes, warnings (notice) for ambiguous expressions in vlib/math/bits during tests:

$ ./v -stats -W test vlib/math/bits
(...)
vlib/math/bits/bits.v:109:52: notice: ambiguous expression. use `()` to ensure correct order of operations
  107 | @[direct_array_access]
  108 | pub fn ones_count_32(x u32) int {
  109 |     return int(pop_8_tab[x >> 24] + pop_8_tab[x >> 16 & 0xff] + pop_8_tab[x >> 8 & 0xff] +
      |                                                       ^
  110 |         pop_8_tab[x & u32(0xff)])
  111 | }
vlib/math/bits/bits.v:134:24: notice: ambiguous expression. use `()` to ensure correct order of operations
  132 |     // more, but it saves at best one instruction, so we leave
  133 |     // it alone for clarity.
  134 |     mut y := (x >> u64(1) & (m0 & max_u64)) + (x & (m0 & max_u64))
      |                           ^
  135 |     y = (y >> u64(2) & (m1 & max_u64)) + (y & (m1 & max_u64))
  136 |     y = ((y >> 4) + y) & (m2 & max_u64)
vlib/math/bits/bits.v:135:19: notice: ambiguous expression. use `()` to ensure correct order of operations
  133 |     // it alone for clarity.
  134 |     mut y := (x >> u64(1) & (m0 & max_u64)) + (x & (m0 & max_u64))
  135 |     y = (y >> u64(2) & (m1 & max_u64)) + (y & (m1 & max_u64))
      |                      ^
  136 |     y = ((y >> 4) + y) & (m2 & max_u64)
  137 |     y += y >> 8
(...)

With fix, no more warnings for ambiguous expression, only notice for "shifting a value from a signed type int" (no fix for theses warnings).

$ ./v -stats -W test vlib/math/bits
---- Testing... ----------------------------------------------------------------------------------------------------------------------------
vlib/math/bits/bits_test.v:18:29: notice: shifting a value from a signed type `int` can change the sign
   16 |     for x in 0 .. 8 {
   17 |         // C.printf("x:%02x lz: %d cmp: %d\n", i << x, leading_zeros_8(i << x), 7-x)
   18 |         assert leading_zeros_8(u8(i << x)) == 7 - x
      |                                   ^
   19 |     }
   20 |
vlib/math/bits/bits_test.v:51:8: notice: shifting a value from a signed type `int` can change the sign
   49 |         // C.printf("x:%02x lz: %llu cmp: %d\n", u8(i), ones_count_8(u8(i)), x)
   50 |         assert ones_count_8(u8(i)) == x
   51 |         i = (i << 1) + 1
      |              ^
   52 |     }
   53 |
vlib/math/bits/bits_test.v:59:8: notice: shifting a value from a signed type `int` can change the sign
   57 |         // C.printf("x:%04x lz: %llu cmp: %d\n", u16(i), ones_count_16(u16(i)), x)
   58 |         assert ones_count_16(u16(i)) == x
   59 |         i = (i << 1) + 1
      |              ^
   60 |     }
   61 |
vlib/math/bits/bits_test.v:67:8: notice: shifting a value from a signed type `int` can change the sign
   65 |         // C.printf("x:%08x lz: %llu cmp: %d\n", u32(i), ones_count_32(u32(i)), x)
   66 |         assert ones_count_32(u32(i)) == x
   67 |         i = (i << 1) + 1
      |              ^
   68 |     }
   69 |
vlib/math/bits/bits_test.v:103:8: notice: shifting a value from a signed type `int` can change the sign
  101 |         // C.printf("x:%02x lz: %llu cmp: %d\n", u8(i), reverse_8(u8(i)), rv)
  102 |         assert reverse_8(u8(i)) == rv
  103 |         i = (i << 1) + 1
      |              ^
  104 |     }
  105 |
vlib/math/bits/bits_test.v:119:8: notice: shifting a value from a signed type `int` can change the sign
  117 |         // C.printf("x:%04x lz: %llu cmp: %d\n", u16(i), reverse_16(u16(i)), rv)
  118 |         assert reverse_16(u16(i)) == rv
  119 |         i = (i << 1) + 1
      |              ^
  120 |     }
  121 |
vlib/math/bits/bits_test.v:135:8: notice: shifting a value from a signed type `int` can change the sign
  133 |         // C.printf("x:%08x lz: %llu cmp: %d\n", u32(i), reverse_32(u32(i)), rv)
  134 |         assert reverse_32(u32(i)) == rv
  135 |         i = (i << 1) + 1
      |              ^
  136 |     }
  137 |
checker summary: 0 V errors, 0 V warnings, 7 V notices
        V  source  code size:      30340 lines,     139498 tokens,     816501 bytes,   288 types,    12 modules,   135 files
generated  target  code size:      11765 lines,     436028 bytes
compilation took: 314.856 ms, compilation speed: 96361 vlines/s, cgen threads: 7
running tests in: /home/fox/dev/Perso/vlang.git/vlib/math/bits/bits_test.v
      OK    [1/2]     0.162 ms  1289 asserts | math.bits.test_bits()
      OK    [2/2]     0.001 ms     4 asserts | math.bits.test_div_64_edge_cases()
     Summary for running V tests in "bits_test.v": 1293 passed, 1293 total. Elapsed time: 0 ms.

 OK     328.813 ms vlib/math/bits/bits_test.v
--------------------------------------------------------------------------------------------------------------------------------------------
Summary for all V _test.v files: 1 passed, 1 total. Elapsed time: 329 ms, on 1 job. Comptime: 0 ms. Runtime: 328 ms.

[huly-for-github]

Connected to Huly®: V_0.6-23253

[spytheman]

Excellent work.