brp-sign-kmodules.in: fix couple of shellcheck warnings

SC2162 ("read without -r will mangle backslashes") and SC2086: ("Double
quote to prevent globbing and word splitting").  These actually seem to
be harmless in our case.

scripts/brp-sign-kmodules.in

@@ -88,7 +88,7 @@ fi
 
 find "$RPM_BUILD_ROOT/lib/modules" -name '*.ko*' > .kmodules
 num=$(wc -l < .kmodules)
-if [ $num -eq 0 ]; then
+if [ "$num" -eq 0 ]; then
 	Warning "No kernel modules found for singing."
 	exit 0
 fi
@@ -104,7 +104,7 @@ rm "$t"
 cd "$RPM_BUILD_ROOT"
 
 # Determine if we should uncompress.
-read f < .kmodules
+read -r f < .kmodules
 rezip=
 if [ -z "${f#*.ko.[gx]z}" ]; then
 	rezip=${f##*.}