EGL: make max cache key size BoardConfig-able

This change makes the maximum EGL blob cache key size configurable via a
BoardConfig.

Change-Id: Ic669cd25fc743662bd4f13aab62354fc3d54560c
diff --git a/opengl/libs/Android.mk b/opengl/libs/Android.mk
index eea79f8..31bfcd7 100644
--- a/opengl/libs/Android.mk
+++ b/opengl/libs/Android.mk
@@ -57,6 +57,10 @@
   LOCAL_CFLAGS += -DMAX_EGL_CACHE_ENTRY_SIZE=$(MAX_EGL_CACHE_ENTRY_SIZE)
 endif
 
+ifneq ($(MAX_EGL_CACHE_KEY_SIZE),)
+  LOCAL_CFLAGS += -DMAX_EGL_CACHE_KEY_SIZE=$(MAX_EGL_CACHE_KEY_SIZE)
+endif
+
 ifneq ($(MAX_EGL_CACHE_SIZE),)
   LOCAL_CFLAGS += -DMAX_EGL_CACHE_SIZE=$(MAX_EGL_CACHE_SIZE)
 endif