build: fix missing function prototype on older gcc

vtjnash · vtjnash · commit ef17985df6ee · 2020-02-13T16:35:05.000-05:00
The ffs function is not always available under that name, use instead the compiler name for it which may always be used.
diff --git a/src/gc.h b/src/gc.h
@@ -372,7 +372,7 @@ STATIC_INLINE unsigned ffs_u32(uint32_t bitvec)
     _BitScanForward(&j, bitvec);
     return j;
 #else
-    return ffs(bitvec) - 1;
+    return __builtin_ffs(bitvec) - 1;
 #endif
 }
 #endif

Original file line number	Diff line number	Diff line change
`@@ -372,7 +372,7 @@ STATIC_INLINE unsigned ffs_u32(uint32_t bitvec)`
`372`	`372`	`_BitScanForward(&j, bitvec);`
`373`	`373`	`return j;`
`374`	`374`	`#else`
`375`		`- return ffs(bitvec) - 1;`
	`375`	`+ return __builtin_ffs(bitvec) - 1;`
`376`	`376`	`#endif`
`377`	`377`	`}`
`378`	`378`	`#endif`