chore: stage-1 gcc only needs to support C to build musl

Author: mhx

.docker/install-toolchain.sh

@@ -153,7 +153,7 @@ for target_arch in ${TARGET_ARCH_STR//,/ }; do
                 --target=$TARGET --prefix=$PREFIX --with-sysroot=$SYSROOT ${GCC_CONFIGURE_ARGS} --with-newlib --without-headers \
                 --disable-nls --disable-shared --disable-multilib --disable-decimal-float --disable-threads \
                 --disable-libatomic --disable-libgomp --disable-libquadmath --disable-libssp --disable-libvtv \
-                --disable-libstdcxx --enable-languages=c,c++ ${GCC_NODOCS}
+                --disable-libstdcxx --enable-languages=c ${GCC_NODOCS}
             make -j"$(nproc)" all-gcc ${GCC_NODOCS}
             make -j"$(nproc)" all-target-libgcc ${GCC_NODOCS}
             make install-gcc