x11-misc/xxkb: force gcc -E for imake's generation

Requires traditional cpp support and is broken in all sort of ways
with clang-cpp / -E. Can still use clang & friends for everything else.

Ideally these packages need to be built another way or last rited,
imake will just accumulate more problems.

Closes: https://bugs.gentoo.org/870739
Signed-off-by: Ionen Wolkens <ionen@gentoo.org>

x11-misc/xxkb/xxkb-1.11.1-r1.ebuild

@@ -1,4 +1,4 @@
-# Copyright 1999-2021 Gentoo Authors
+# Copyright 1999-2022 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=7
@@ -31,6 +31,7 @@ RDEPEND="
 DEPEND="${RDEPEND}"
 BDEPEND="
 	app-text/rman
+	sys-devel/gcc
 	>=x11-misc/imake-1.0.8-r1
 	svg? ( virtual/pkgconfig )
 "
@@ -49,7 +50,7 @@ src_prepare() {
 
 src_configure() {
 	CC="$(tc-getBUILD_CC)" LD="$(tc-getLD)" \
-		IMAKECPP="${IMAKECPP:-$(tc-getCPP)}" \
+		IMAKECPP="${IMAKECPP:-${CHOST}-gcc -E}" \
 		xmkmf $(usex svg -DWITH_SVG_SUPPORT '') || die
 }