Fix typo in previous compiler patch for gcc 3.x

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/compiler.h b/compiler.h
index 0d17ae1..8a3fe63 100644
--- a/compiler.h
+++ b/compiler.h
@@ -3,7 +3,7 @@
 
 #if __GNUC__ >= 4
 #include "compiler-gcc4.h"
-#elif __GNUC == 3
+#elif __GNUC__ == 3
 #include "compiler-gcc3.h"
 #else
 #error Compiler too old, need gcc at least gcc 3.x