findutils: Use C locale to run ptests

Ensure consistent locale setting, since we are not
using make environemnt to run the tests like
upstream does. The test scripts are run explicitly

This fixes a problem with musl ptest runs where the
locale-driven quoting ends up using C.UTF-8 quotes
in gnulib’s quotearg() end up with curly quotes
instead of ASCII quote character which is expected
and result is reported as failure even though numbers
are matching.

Fixes:

-find: invalid group name or GID argument to -group: '4294967296'
+find: invalid group name or GID argument to -group: ‘4294967296’

FAIL: tests/find/user-group-max.sh

(From OE-Core rev: 0e60d1169ee0ae0e6651951e9a917a0e24bee157)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/findutils/findutils/run-ptest

@@ -13,6 +13,9 @@ export built_programs="find xargs locate updatedb"
 # this gets substituted by sed during build
 export VERSION="__run_ptest_version__"
 
+# Force ASCII quotes so exp vs err comparisons are stable across locales.
+export LC_ALL=C
+
 for f in tests/*/*.sh; do
 	bash $f ;
 	case $? in