utils: build sha1/disk cache only with Android/Autoconf

Earlier commit imported a SHA1 implementation and relaxed the SHA1 and
disk cache handling, broking the Windows builds.

Restrict things for now until we get to a proper fix.

Fixes: d1efa09d342 "util: import sha1 implementation from OpenBSD"
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/Android.common.mk b/Android.common.mk
index ed5118a..a75d4e7 100644
--- a/Android.common.mk
+++ b/Android.common.mk
@@ -43,6 +43,7 @@
 	-DANDROID_VERSION=0x0$(MESA_ANDROID_MAJOR_VERSION)0$(MESA_ANDROID_MINOR_VERSION)
 
 LOCAL_CFLAGS += \
+	-DENABLE_SHADER_CACHE \
 	-D__STDC_LIMIT_MACROS \
 	-DHAVE___BUILTIN_EXPECT \
 	-DHAVE___BUILTIN_FFS \