cc/gcc: Apply CT_CC_GCC_DISABLE_PCH to do_cc_core.
Otherwise, users have to input --disable-libstdcxx-pch option
when building bare-metal CANADIAN C++ compiler.
Reviewed-by: Michael Hope
Signed-off-by: Zhenqiang Chen <zhenqiang.chen@linaro.org>
(transplanted from e3e1c9d45bddfbfb433ee9d583faf42fa31f50c0)
1 # Options specific to crosstool-NG acting as a backend
5 option env="CT_IS_A_BACKEND"
9 default y if IS_A_BACKEND = "y" || IS_A_BACKEND = "Y"
13 option env="CT_BACKEND_ARCH"
17 option env="CT_BACKEND_KERNEL"
21 option env="CT_BACKEND_LIBC"