[PATCH] Use CC to determine if gcc is used

[Heiko Becker <heirecka@xxxxxxxxxxx>]

I ran into this with gcc-5.1 and CPP set to x86_64-pc-linux-gnu-cpp
which isn't catched by the intended case branch and caused zsh to be
miscompiled in the process.
---
 Src/zsh.mdd | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Src/zsh.mdd b/Src/zsh.mdd
index 71dd613..3c8c355 100644
--- a/Src/zsh.mdd
+++ b/Src/zsh.mdd
@@ -28,8 +28,8 @@ hdrdeps="zshcurses.h zshterm.h"
 # on the option to remove them being the same.
 signames.c: signames1.awk signames2.awk ../config.h @SIGNAL_H@
 	$(AWK) -f $(sdir)/signames1.awk @SIGNAL_H@ >sigtmp.c
-	case "$(CPP)" in \
-	gcc*) \
+	case "$(CC)" in \
+	*gcc*) \
 	$(CPP) -P sigtmp.c >sigtmp.out;; \
 	*) \
 	$(CPP) sigtmp.c >sigtmp.out;; \
-- 
2.3.3