build: do not depend on svn any more

LEDE does not need svn to build any more, remove the prerequisite check.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

include/prereq-build.mk

@@ -154,9 +154,6 @@ $(eval $(call SetupHostCommand,python,Please install Python 2.x, \
 	python2 -V 2>&1 | grep Python, \
 	python -V 2>&1 | grep Python))
 
-$(eval $(call SetupHostCommand,svn,Please install the Subversion client, \
-	svn --version | grep Subversion))
-
 $(eval $(call SetupHostCommand,git,Please install Git (git-core) >= 1.7.12.2, \
 	git --exec-path | xargs -I % -- grep -q -- --recursive %/git-submodule))