Split build date into a separate DEFINE

Makefile

@@ -114,7 +114,7 @@ include $(TMK_PATH)/protocol/lufa.mk
 include $(TMK_PATH)/common.mk
 include $(TMK_PATH)/rules.mk
 
-GIT_VERSION := $(shell git describe --abbrev=6 --dirty --always --tags 2>/dev/null || date +"%Y-%m-%d")
-
+GIT_VERSION := $(shell git describe --abbrev=6 --dirty --always --tags 2>/dev/null)
+BUILD_DATE := $(shell date +"%Y-%m-%d-%H:%M:%S")
 OPT_DEFS += -DQMK_KEYBOARD=\"$(KEYBOARD)\" -DQMK_KEYMAP=\"$(KEYMAP)\"
-OPT_DEFS += -DQMK_VERSION=\"$(GIT_VERSION)\"
+OPT_DEFS += -DQMK_VERSION=\"$(GIT_VERSION)\" -DQMK_BUILDDATE=\"$(BUILD_DATE)\"

keyboard/planck/keymaps/cbbrowne/keymap.c

@@ -138,7 +138,7 @@ const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt)
     break;
   case M_VERSION:
     if (record->event.pressed) {
-      SEND_STRING(QMK_KEYBOARD "/" QMK_KEYMAP "@" QMK_VERSION);
+      SEND_STRING(QMK_KEYBOARD "/" QMK_KEYMAP "@" QMK_VERSION "@" QMK_BUILDDATE);
     }
     break;
   case M_RANDDIGIT: