gcc: add patches for or1k specific gcc version

gcc: add patches for or1k specific gcc version

This commit adds a number of patches from package/gcc/5.4.0 to
package/gcc/musl-5.4.0, so that they apply to the or1k specific gcc
version. All patches from package/gcc/5.4.0 that are not architecture
specific and not related to the musl C library have been added to
package/gcc/musl-5.4.0/.

Note that doing a symbolic link does not work, as some patches from
package/gcc/5.4.0 do not apply as-is to the or1k gcc version.

The most important patch is 850-libstdcxx-uclibc-c99.patch, which fixes
a number of build issues.

Fixes:

  http://autobuild.buildroot.net/results/eebf4ce5ecb896e54912cfa21268e81ff5fb6593/
  (alljoyn)

  http://autobuild.buildroot.net/results/8dbf406898a59e36ac6a1e16f543b6260da775c8/
  (jsoncpp)

  http://autobuild.buildroot.net/results/206fbd5473c8c6840489990cb2552566c62ef3c8/
  (dawgic)

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