Use BSD grep for builds with toybox

- Include symlinks for egrep and fgrep

Change-Id: I78e27f95efa143fa63def02c9e72af567833aefe
diff --git a/prebuilt/Android.mk b/prebuilt/Android.mk
index 4d67e5b..b63935a 100644
--- a/prebuilt/Android.mk
+++ b/prebuilt/Android.mk
@@ -21,6 +21,11 @@
     RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/sh
     RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libcrypto.so
     ifeq ($(shell test $(PLATFORM_SDK_VERSION) -ge 23; echo $$?),0)
+        RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/grep
+        LOCAL_POST_INSTALL_CMD += $(hide) if [ -e "$(TARGET_RECOVERY_ROOT_OUT)/sbin/egrep" ]; then \
+                                    rm $(TARGET_RECOVERY_ROOT_OUT)/sbin/egrep; fi; ln -sr $(TARGET_RECOVERY_ROOT_OUT)/sbin/grep $(TARGET_RECOVERY_ROOT_OUT)/sbin/egrep; \
+                                    if [ -e "$(TARGET_RECOVERY_ROOT_OUT)/sbin/fgrep" ]; then \
+                                    rm $(TARGET_RECOVERY_ROOT_OUT)/sbin/fgrep; fi; ln -sr $(TARGET_RECOVERY_ROOT_OUT)/sbin/grep $(TARGET_RECOVERY_ROOT_OUT)/sbin/fgrep;
         RELINK_SOURCE_FILES += $(TARGET_RECOVERY_ROOT_OUT)/sbin/toybox
         ifneq ($(wildcard external/zip/Android.mk),)
             RELINK_SOURCE_FILES += $(TARGET_OUT_OPTIONAL_EXECUTABLES)/zip