Fix negation in shell tests (#14662)

According to documentation the `if test ! ...` is preferred to
`if ! test ...`. The later is not portable:
https://www.gnu.org/software/autoconf/manual/autoconf-2.72/autoconf.html

scripts/dev/genfiles

@@ -95,7 +95,7 @@ else
 fi
 
 # Check if make exists.
-if ! test -x "$(command -v $MAKE)"; then
+if test ! -x "$(command -v $MAKE)"; then
   echo "genfiles: make not found. Please install make to generate files." >&2
   exit 1
 fi