devel/glib20: unbreak some C++ consumers after 27fe5eff

$ make -C lang/gjs
[...]
../util/log.cpp:106:25: error: no matching function for call to 'strcmp'
    if (debug_output && g_str_equal(debug_output, "stderr")) {
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/include/glib-2.0/glib/ghash.h:165:30: note: expanded from macro 'g_str_equal'
 #define g_str_equal(v1, v2) (strcmp ((gconstpointer) (v1), (gconstpointer) (v2)) == 0)
                              ^~~~~~
/usr/include/string.h:82:6: note: candidate function not viable: cannot convert argument of incomplete type 'gconstpointer' (aka 'const void *') to 'const char *' for 1st argument
int      strcmp(const char *, const char *) __pure;
         ^

Reported by:	fluffy, cmt
Regressed by:	https://gitlab.gnome.org/GNOME/glib/-/commit/b46ed37c972f

devel/glib20/Makefile

 PORTNAME=	glib
 DISTVERSION=	2.74.2
+PORTREVISION=	1
 PORTEPOCH=	2
 CATEGORIES=	devel
 MASTER_SITES=	GNOME

devel/glib20/files/patch-glib_ghash.h

+https://gitlab.gnome.org/GNOME/glib/-/issues/2820
+
+--- glib/ghash.h.orig	2022-11-24 12:29:05 UTC
++++ glib/ghash.h
+@@ -162,7 +162,7 @@ gboolean g_str_equal    (gconstpointer  v1,
+                          gconstpointer  v2);
+ 
+ /* Macro for optimization in the case it is not used as callback function */
+-#define g_str_equal(v1, v2) (strcmp ((gconstpointer) (v1), (gconstpointer) (v2)) == 0)
++#define g_str_equal(v1, v2) (strcmp ((const char *) (v1), (const char *) (v2)) == 0)
+ 
+ GLIB_AVAILABLE_IN_ALL
+ guint    g_str_hash     (gconstpointer  v);