gcc: configure options cleanup

drop gcc4-compatible libstdcxx string format

GCC 5.1 included a change to how strings operated to be compatible with
the 2011 C++ standard. It gave an option to use the previous method by
setting:

  --with-default-libstdcxx-abi=gcc4-compatible

The default is to have this value set to "new", and has been for several
years.

See https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html
for further details.

drop --enable-c99 from gcc:host configure

This doesn't appear in ./configure. It either does nothing, or works
against the default of gnu11 since GCC5.

Signed-off-by: Ian Leonard <antonlacon@gmail.com>

packages/lang/gcc/package.mk

@@ -39,7 +39,6 @@ GCC_COMMON_CONFIGURE_OPTS="--target=${TARGET_NAME} \
                            --disable-multilib \
                            --disable-nls \
                            --enable-checking=release \
-                           --with-default-libstdcxx-abi=gcc4-compatible \
                            --without-ppl \
                            --without-cloog \
                            --disable-libada \
@@ -70,7 +69,6 @@ PKG_CONFIGURE_OPTS_HOST="${GCC_COMMON_CONFIGURE_OPTS} \
                          --enable-tls \
                          --enable-shared \
                          --disable-static \
-                         --enable-c99 \
                          --enable-long-long \
                          --enable-threads=posix \
                          --disable-libstdcxx-pch \