cross compiling with different toolchain type

[Johan Vos]

Hi,

I just want to make sure there is still a limitation in place where the
toolchain type of a cross compiler must equal the toolchain type of the
build compiler?
I'm configuring a build for Android (aarch64-linux) and I am using the
clang toolchain type for doing the cross compilation, while I'm using gcc
as the build compiler. However, I get errors running configure:

configure: The BuildC compiler (located as /usr/bin/cc) does not seem to be
the required clang compiler.

Looking into toolchain.m4, this sounds fair to me, as the BuildC compiler
(line 916 and below) is also tested
with TOOLCHAIN_EXTRACT_COMPILER_VERSION(BUILD_CC, [BuildC]) which
unconditionally checks for the $TOOLCHAIN_TYPE.

Hence, it seems cross-compiling using a clang compiler, while using gcc as
the build compiler is not possible.
That's by no means a showstopper to me, I just want to double check that
I'm not missing something.

Thanks,

- Johan