EomMetadataDetails: Don't install header file

This is not really useful for plugins.

origin commit:
https://gitlab.gnome.org/GNOME/eog/commit/5a497db

Author: fxri

src/Makefile.am

@@ -111,9 +111,11 @@ libeom_la_SOURCES =			\
 
 if HAVE_EXIF
 INST_H_FILES +=				\
-	eom-metadata-details.h  \
 	eom-exif-util.h
 
+NOINST_H_FILES +=			\
+	eom-metadata-details.h
+
 libeom_c_files +=			\
 	eom-metadata-details.c  \
 	eom-exif-util.c
@@ -124,7 +126,7 @@ if HAVE_EXEMPI
 # is only listed once in INST_H_FILES
 # or the build will break with automake-1.11
 if !HAVE_EXIF
-INST_H_FILES +=				\
+NOINST_H_FILES +=				\
 	eom-metadata-details.h
 endif !HAVE_EXIF
 libeom_la_SOURCES +=			\

src/eom-metadata-details.h

@@ -54,15 +54,19 @@ struct _EomMetadataDetailsClass {
 	GtkTreeViewClass parent_class;
 };
 
+G_GNUC_INTERNAL
 GType               eom_metadata_details_get_type    (void) G_GNUC_CONST;
 
+G_GNUC_INTERNAL
 GtkWidget          *eom_metadata_details_new         (void);
 
 #if HAVE_EXIF
+G_GNUC_INTERNAL
 void                eom_metadata_details_update      (EomMetadataDetails *details,
                                                       ExifData       *data);
 #endif
 #if HAVE_EXEMPI
+G_GNUC_INTERNAL
 void                eom_metadata_details_xmp_update  (EomMetadataDetails *details,
                                                       XmpPtr          xmp_data);
 #endif