[PATCH v2] kbuild: install-extmod-build: Properly fix CC expansion when ccache is used

[Abel Vesa <abel.vesa@linaro.org>]

Currently, when cross-compiling and ccache is used, the expanding of CC
turns out to be without any quotes, leading to the following error:

make[4]: *** No rule to make target 'aarch64-linux-gnu-gcc'.  Stop.
make[3]: *** [Makefile:2164: run-command] Error 2

And it makes sense, because after expansion it ends up like this:

make run-command KBUILD_RUN_COMMAND=+$(MAKE) \
HOSTCC=ccache aarch64-linux-gnu-gcc VPATH= srcroot=. $(build)= ...

So add another set of double quotes to surround whatever CC expands to
to make sure the aarch64-linux-gnu-gcc isn't expanded to something that
looks like an entirely separate target.

Fixes: 140332b6ed72 ("kbuild: fix linux-headers package build when $(CC) cannot link userspace")
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
---
Changes in v2:
- Moved the new double quotes inside of single ones, to be able
  to drop the escape, like Nathan suggested.
- Re-worded the commit message according to the above change.
- Link to v1: https://lore.kernel.org/r/20251110-kbuild-install-extmod-build-fix-cc-expand-third-try-v1-1-5c0ddb1c67a8@linaro.org
---
 scripts/package/install-extmod-build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/package/install-extmod-build b/scripts/package/install-extmod-build
index 054fdf45cc37a8717444b8094daf3e1150a8ccf5..2576cf7902dbbfcd82ea690aac1b2a246b3a6a30 100755
--- a/scripts/package/install-extmod-build
+++ b/scripts/package/install-extmod-build
@@ -63,7 +63,7 @@ if [ "${CC}" != "${HOSTCC}" ]; then
 	# Clear VPATH and srcroot because the source files reside in the output
 	# directory.
 	# shellcheck disable=SC2016 # $(MAKE) and $(build) will be expanded by Make
-	"${MAKE}" run-command KBUILD_RUN_COMMAND='+$(MAKE) HOSTCC='"${CC}"' VPATH= srcroot=. $(build)='"$(realpath --relative-to=. "${destdir}")"/scripts
+	"${MAKE}" run-command KBUILD_RUN_COMMAND='+$(MAKE) HOSTCC="'"${CC}"'" VPATH= srcroot=. $(build)='"$(realpath --relative-to=. "${destdir}")"/scripts
 
 	rm -f "${destdir}/scripts/Kbuild"
 fi

---
base-commit: 9c0826a5d9aa4d52206dd89976858457a2a8a7ed
change-id: 20251109-kbuild-install-extmod-build-fix-cc-expand-third-try-2cb1540cadbf

Best regards,
-- 
Abel Vesa <abel.vesa@linaro.org>