gcc: gcc 4.9.x disable libsanitize

gcc: gcc 4.9.x disable libsanitize

gcc 4.9.x enables building of libsanitize

- libsanitize needs some headers that are not available
  in uclibc (netrom/netrom.h)

according to buildroot project:
- build fail with musl
- need wordexp with uclibc which increases uclibc size
http://git.buildroot.net/buildroot/commit/?id=5f4d658d888b539de9a6247ae5b1a0999de5d4ec
http://git.buildroot.net/buildroot/commit/?id=554e29e267e6b36a0fd78c82cbad2c82d939eb7f

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@42767 3c298f89-4303-0410-b956-a3cf2f4a3e73