icu: fix cross build.

srcpkgs/icu/template

@@ -21,6 +21,7 @@ pre_configure() {
 	if [ "$CROSS_BUILD" ]; then
 		# Configure and build for host.
 		mkdir host-build
+		(
 		cd host-build
 		env CC=cc LD=ld CXX=g++ AR=ar RANLIB=ranlib \
 			AS=as STRIP=strip CFLAGS="-Os" CXXFLAGS="-Os" \
@@ -31,6 +32,7 @@ pre_configure() {
 		make DESTDIR=${wrksrc}/host-icu install
 		mv ${wrksrc}/host-icu/sbin/* ${wrksrc}/host-icu/bin
 		make distclean
+		)
 	fi
 
 	# libicudata must be linked to libc, otherwise it's soft-float on ARM.