infrastructure: only require download tools when needed

Instead of having to require svn, git or bzr unconditionally, only
require them when one package needs them to be downloaded.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/Makefile.package.in

@@ -504,9 +504,19 @@ $$($(2)_TARGET_DIRCLEAN):		PKG=$(2)
 # configuration
 
 ifeq ($$(BR2_PACKAGE_$(2)),y)
+
 TARGETS += $(1)
-endif
-endef
+
+ifeq ($$($(2)_SITE_METHOD),svn)
+DL_TOOLS_DEPENDENCIES += svn
+else ifeq ($$($(2)_SITE_METHOD),git)
+DL_TOOLS_DEPENDENCIES += git
+else ifeq ($$($(2)_SITE_METHOD),bzr)
+DL_TOOLS_DEPENDENCIES += bzr
+endif # SITE_METHOD
+
+endif # BR2_PACKAGE_$(2)
+endef # GENTARGETS_INNER
 
 ################################################################################
 # GENTARGETS -- the target generator macro for generic packages

toolchain/dependencies/dependencies.mk

@@ -10,9 +10,16 @@ ifeq ($(BR2_STRIP_sstrip),y)
 DEPENDENCIES_HOST_PREREQ+=sstrip_host
 endif
 
+# Remove duplicate entries from $(DL_TOOLS_DEPENDENCIES)
+DL_TOOLS = \
+	$(findstring svn,$(DL_TOOLS_DEPENDENCIES)) \
+	$(findstring git,$(DL_TOOLS_DEPENDENCIES)) \
+	$(findstring bzr,$(DL_TOOLS_DEPENDENCIES))
+
 dependencies: $(DEPENDENCIES_HOST_PREREQ)
 	@HOSTCC="$(firstword $(HOSTCC))" MAKE="$(MAKE)" \
 		CONFIG_FILE="$(CONFIG_DIR)/.config" \
+		DL_TOOLS="$(DL_TOOLS)" \
 		$(TOPDIR)/toolchain/dependencies/dependencies.sh
 
 dependencies-source:

toolchain/dependencies/dependencies.sh

@@ -132,7 +132,7 @@ if ! $SHELL --version 2>&1 | grep -q '^GNU bash'; then
 fi;
 
 # Check that a few mandatory programs are installed
-for prog in awk bison flex msgfmt makeinfo patch gzip bzip2 perl tar wget cpio python svn unzip ; do
+for prog in awk bison flex msgfmt makeinfo patch gzip bzip2 perl tar wget cpio python unzip ${DL_TOOLS} ; do
     if ! which $prog > /dev/null ; then
 	/bin/echo -e "\nYou must install '$prog' on your build machine";
 	if test $prog = "makeinfo" ; then