builtin.closure: improve ppc64le closure if PIE (#26172)

Author: tankf33der

vlib/builtin/closure/closure.c.v

@@ -82,6 +82,7 @@ pub const closure_thunk = $if amd64 {
         0xf8, 0xbf, 0xce, 0x39,	// addi   %r14, %r14, -16392
         0x00, 0x00, 0xce, 0xc9,	// lfd    %f14, 0(%r14)
         0x08, 0x00, 0xce, 0xe9,	// ld     %r14, 8(%r14)
+        0x78, 0x73, 0xcc, 0x7d,	// mr     %r12, %r14
         0xa6, 0x03, 0x08, 0x7c,	// mtlr   %r0
         0xa6, 0x03, 0xc9, 0x7d,	// mtctr  %r14
         0x20, 0x04, 0x80, 0x4e,	// bctr