mk: fetch.mk: Clone git sources with --recurse-submodules

This eliminates the separate git call for submodules along with the need
for package Makefiles to request this.

Signed-off-by: Phil Sutter <phil@nwl.cc>

mk/fetch.mk

@@ -80,12 +80,9 @@ $(1):
 			;; \
 		  esac ;\
 		else \
-		  git clone --progress --depth 1 $${PKG_SITES} $${PKG_NAME}-$${PKG_VERSION} $(DL_TRACE); \
+		  git clone --progress --depth 1 --recurse-submodules $${PKG_SITES} $${PKG_NAME}-$${PKG_VERSION} $(DL_TRACE); \
 		  if [ $$$$? -ne 0 ]; then echo "git clone error"; exit 1; fi; \
 		fi; \
-		if [ ! -z "$${PKG_GIT_SUBMODULE}" ]; then \
-			(cd $${PKG_NAME}-$${PKG_VERSION}; git submodule update --init --recursive) $(DL_TRACE); \
-		fi; \
 		rm -rf $${PKG_NAME}-$${PKG_VERSION}/.git; \
 		PATH='$(HOST_PATH)' tar czf $${PKG_NAME}-$${PKG_VERSION}.tar.gz $${PKG_NAME}-$${PKG_VERSION}; \
 		touch $$$${filename}.nohash; \