buildroot: silence ./configure step when building with 'make -s'

We have been passing -q to ./configure when using 'make -s' for
packages using Makefile.autotools.in for some time. Do the same
for packages using autotools, but not using the
Makefile.autotools.in infrastructure, taking care to not do it
for packages with hand written configure scripts.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/libelf/libelf.mk

@@ -34,7 +34,7 @@ $(LIBELF_DIR)/.configured: $(LIBELF_DIR)/.unpacked
 		libelf_cv_working_memmove=yes \
 		mr_cv_target_elf=yes \
 		libelf_64bit=yes \
-		./configure \
+		./configure $(QUIET) \
 		--target=$(GNU_TARGET_NAME) \
 		--host=$(GNU_TARGET_NAME) \
 		--build=$(GNU_HOST_NAME) \