tests: default to 'cc' if CC not set

By default FreeBSD does not have 'gcc' in the PATH (on common platforms).
As on Linux 'cc' is available as a link to the default compiler (Clang or
GCC), so just use 'cc'.

Signed-off-by: Ed Maste <emaste@freebsd.org>
Message-Id: <20191115155108.39488-1-emaste@freefall.freebsd.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tests/run_tests.sh

@@ -4,7 +4,7 @@ SRCDIR=`dirname "$0"`
 . "$SRCDIR/testutils.sh"
 
 if [ -z "$CC" ]; then
-    CC=gcc
+    CC=cc
 fi
 
 # stat differs between platforms