fix typo to make mednafen compile on powerpc

from brad

emulators/mednafen/Makefile

@@ -4,6 +4,7 @@ COMMENT =	emulates numerous game consoles
 VERSION =	1.29.0
 DISTNAME =	mednafen-${VERSION}
 PKGNAME =	mednafen-${VERSION:C/-UNSTABLE//}
+REVISION =	0
 
 CATEGORIES =	emulators games
 HOMEPAGE =	https://mednafen.github.io

emulators/mednafen/patches/patch-src_snes_src_lib_libco_ppc_c

@@ -0,0 +1,14 @@
+snes/src/lib/libco/ppc.c:396:21: error: expected value in expression
+
+Index: src/snes/src/lib/libco/ppc.c
+--- src/snes/src/lib/libco/ppc.c.orig
++++ src/snes/src/lib/libco/ppc.c
+@@ -393,7 +393,7 @@ void co_delete(cothread_t t) {
+ }
+ 
+ static void co_init_(void) {
+-  #if LIBCO_MPROTECT
++  #ifdef LIBCO_MPROTECT
+   long page_size = sysconf(_SC_PAGESIZE);
+   if(page_size > 0) {
+     uintptr_t align = page_size;