message: Update gmp config
diff: package=gmp
  $(package)_version=6.1.2
  $(package)_sha256_hash=87b565e89a9a684fe4ebeeddb8399dce2599f9c9049854ca8c0dfbdea0e21912
  -$(package)_build_subdir=$(package)-$($(package)_version)
  $(package)_file_name=$(package)-$($(package)_version).tar.xz
  $(package)_download_path=https://gmplib.org/download/$(package)
  +define $(package)_set_vars
  +$(package)_config_opts=--enable-static=yes --enable-shared=no --enable-cxx
  +$(package)_config_opts_linux=--with-pic
  +endef
  +
  +define $(package)_preprocess_cmds
  + cp -f $(BASEDIR)/config.guess $(BASEDIR)/config.sub .
  +endef
  +
  define $(package)_config_cmds
  - ../configure --enable-static=yes --enable-shared=no --enable-cxx -without-readline --host=$(host) --prefix=$(host_prefix) --build=$(build)
  + $($(package)_autoconf)
  endef
  define $(package)_build_cmds
  - $(MAKE) CPPFLAGS='-fPIC'
  + $(MAKE)
  endef
  define $(package)_stage_cmds
  