[OE-core] grub build problems

[Marko Lindqvist]

I've got host compiler that fails on grub configure checks (bug in
system headers that has not manifested itself in any other
compilation). Now, build of grub-efi-native_2.0 recipe fails. It seems
its configure uses host compiler when it's supposed to use oe
cross-compiler.
configure.ac has hack like this (with TARGET_CC set earlier)
# Test the C compiler for the target environment.
...
CC="$TARGET_CC"


One of the problems seems to be that above compiler is then not
consistently used. Many .m4 files have AC_REQUIRE([AC_PROG_CC]) which
resets CC to what autotools usually expect it to be. Removing these
AC_REQUIREs do allow process to progress further, but I'm worried what
ill effects that might have (at least it expects that modified
m4-files from grub-tree are used instead of system ones, even if the
latter has higher serial number).

Another thing I've played with (from the lack of reproducible test
cases cannot really tell if it's needed) is adding dependency to
cross-gcc (one that grub considers "target gcc") as grub build wants
to use also such a thing despite being -native recipe.


 - ML