build system: stop including alloca.h, stdlib.h provides it

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/scripts/basic/fixdep.c b/scripts/basic/fixdep.c
index 165a8c3..19f82df 100644
--- a/scripts/basic/fixdep.c
+++ b/scripts/basic/fixdep.c
@@ -113,7 +113,7 @@
 #include <limits.h>
 #include <ctype.h>
 #include <arpa/inet.h>
-#include <alloca.h>
+//bbox disabled: #include <alloca.h>
 
 /* bbox: not needed
 #define INT_CONF ntohl(0x434f4e46)