gcc: Update to version 5.4.0, change maintainer

Signed-off-by: Noble Pepper <noblepepper@gmail.com>

devel/gcc/patches/970-warn_bug.patch

@@ -0,0 +1,11 @@
+--- a/libgo/runtime/mprof.goc
++++ b/libgo/runtime/mprof.goc
+@@ -403,7 +403,7 @@ func ThreadCreateProfile(p Slice) (n int
+ 
+ func Stack(b Slice, all bool) (n int) {
+ 	byte *pc, *sp;
+-	bool enablegc;
++	bool enablegc = false; /* workaround GCC bug #36550 */
+ 	
+ 	sp = runtime_getcallersp(&b);
+ 	pc = (byte*)(uintptr)runtime_getcallerpc(&b);