gtk4: Compile with gcc for musl/x86_64

[kraj]

There is a gir generation error when compiled with clang

| /mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/recipe-sysroot/usr/include/glib-2.0/gobject/gobject.h:822: syntax error, unexpected INTEGER, expecting identifier in ' do
{ if (builtin_expect (extension ({ int G_PASTE (g_boolean_var, 9); if ((weak_pointer) == ((void*)0)) G_PASTE (g_boolean_var, 9) = 1; else G_PASTE (g_boolean_var, 9) = 0; G_PASTE (
g_boolean_var, 9); }), 1)) ; else g_assertion_message (((gchar*) 0), "/mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/recipe-sysroot/usr/include/glib-2.0/gobject/gobject.h ", 822, ((const char*) (func)), "'" "weak_pointer" "' should be NULL"); } while (0);' at '9' | /mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/recipe-sysroot/usr/include/glib-2.0/gobject/gobject.h:822: syntax error, unexpected ')', expecting identifier or '(' in '
do { if (__builtin_expect (extension ({ int G_PASTE (g_boolean_var, 9); if ((weak_pointer) == ((void*)0)) G_PASTE (g_boolean_var, 9) = 1; else G_PASTE (g_boolean_var, 9) = 0; G_PASTE
(g_boolean_var, 9); }), 1)) ; else g_assertion_message (((gchar*) 0), "/mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/recipe-sysroot/usr/include/glib-2.0/gobject/gobjec
t.h", 822, ((const char*) (func)), "'" "weak_pointer" "' should be NULL"); } while (0);' at ')' | Error relocating /mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/build/gtk/libgtk-4.so.1: unsupported relocation type 37 | Error relocating /mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/build/gtk/libgtk-4.so.1: unsupported relocation type 37 | Error relocating /mnt/b/yoe/master/build/tmp/work/core2-64-yoe-linux-musl/gtk4/4.12.5/build/gtk/libgtk-4.so.1: unsupported relocation type 37 | If the above error message is about missing .so libraries, then setting up GIR_EXTRA_LIBS_PATH in the recipe should help. | (typically like this: GIR_EXTRA_LIBS_PATH="${B}/something/.libs" )

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