Revert "Use repeatable timestamps"

OSX `date` doesn't understand -d

This reverts commit 13ba6e00f4c7e04f1038e94ab98e3ed424daa4fa.

Change-Id: I5970032ff02cc07bd3b087e1eeb5f19b1e4194b4
diff --git a/core/Makefile b/core/Makefile
index cc54836..f7f6e48 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -114,7 +114,7 @@
   ifneq ($(filter eng.%,$(BUILD_NUMBER)),)
     # Trim down BUILD_FINGERPRINT: the default BUILD_NUMBER makes it easily exceed
     # the Android system property length limit (PROPERTY_VALUE_MAX=92).
-    BF_BUILD_NUMBER := $(USER)$(shell date -d "$(BUILD_DATETIME)" +%m%d%H%M)
+    BF_BUILD_NUMBER := $(USER)$(shell date +%m%d%H%M)
   else
     BF_BUILD_NUMBER := $(BUILD_NUMBER)
   endif
@@ -197,7 +197,6 @@
 			PRIVATE_BUILD_DESC="$(PRIVATE_BUILD_DESC)" \
 			BUILD_ID="$(BUILD_ID)" \
 			BUILD_DISPLAY_ID="$(BUILD_DISPLAY_ID)" \
-			BUILD_DATETIME="$(BUILD_DATETIME_FROM_FILE)" \
 			BUILD_NUMBER="$(BUILD_NUMBER_FROM_FILE)" \
 			BOARD_BUILD_SYSTEM_ROOT_IMAGE="$(BOARD_BUILD_SYSTEM_ROOT_IMAGE)" \
 			PLATFORM_VERSION="$(PLATFORM_VERSION)" \
@@ -247,8 +246,8 @@
 	@echo Target vendor buildinfo: $@
 	@mkdir -p $(dir $@)
 	$(hide) echo > $@
-	$(hide) echo ro.vendor.build.date=`date -d "$(BUILD_DATETIME_FROM_FILE)"`>>$@
-	$(hide) echo ro.vendor.build.date.utc=`date -d "$(BUILD_DATETIME_FROM_FILE)" +%s`>>$@
+	$(hide) echo ro.vendor.build.date=`date`>>$@
+	$(hide) echo ro.vendor.build.date.utc=`date +%s`>>$@
 	$(hide) echo ro.vendor.build.fingerprint="$(BUILD_FINGERPRINT_FROM_FILE)">>$@
 endif
 
@@ -263,8 +262,8 @@
 	@echo Target bootimage buildinfo: $@
 	@mkdir -p $(dir $@)
 	$(hide) echo > $@
-	$(hide) echo ro.bootimage.build.date=`date -d "$(BUILD_DATETIME_FROM_FILE)"`>>$@
-	$(hide) echo ro.bootimage.build.date.utc=`date -d "$(BUILD_DATETIME_FROM_FILE)" +%s`>>$@
+	$(hide) echo ro.bootimage.build.date=`date`>>$@
+	$(hide) echo ro.bootimage.build.date.utc=`date +%s`>>$@
 	$(hide) echo ro.bootimage.build.fingerprint="$(BUILD_FINGERPRINT_FROM_FILE)">>$@
 
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