package/git: make _BUG_ condition more clear

As pointed by Peter combined condition of the 2 gcc bugs is potentially
wrong, but as Thomas pointed in this case it's not harmful. Let's fix it
anyway since it's basically wrong even it doesn't cause harm.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/git/git.mk

@@ -67,7 +67,7 @@ endif
 
 GIT_CFLAGS = $(TARGET_CFLAGS)
 
-ifeq ($(BR2_TOOLCHAIN_HAS_GCC_BUG_85180)$(BR2_TOOLCHAIN_HAS_GCC_BUG_93847),y)
+ifneq ($(BR2_TOOLCHAIN_HAS_GCC_BUG_85180)$(BR2_TOOLCHAIN_HAS_GCC_BUG_93847),)
 GIT_CFLAGS += -O0
 endif