toolchain: first step for GCC build
scripts: gcc wrapper to use specs file

The specs file must be pass only once to the gcc command line.
But libtool some time use only CFLAGS, or CPPFLAGS or LDFLAGS or a combinaison of the threes. Then it's impossible to insert inside only one and not inside the threes.
specs-wrapper-gcc in a script that calls gcc with specs file as argument.
specs-wrapper-gcc must be installed inside out/host/toolchain/bin
libc: musl links with static libgcc_eh library
libc: musl include bits/types.h

bits/types.h defines the types __uint_8 __uint_16 ... defined with glibc but not standards