tests: grep portability fixes

We try to avoid using the "-q" or "-e" options, as they are
largely useless, as explained in aadbe44f.

There is one exception for "-e" here, which is in t7701 used
to produce an "or" of patterns. This can be rewritten as an
egrep pattern.

This patch also removes use of "grep -F" in favor of the
more widely available "fgrep".

[sp: Tested on AIX 5.3 by Mike Ralphson,
     Tested on MinGW by Johannes Sixt]

Signed-off-by: Jeff King <peff@peff.net>
Tested-by: Mike Ralphson <mike@abacus.co.uk>
Tested-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
diff --git a/t/t9500-gitweb-standalone-no-errors.sh b/t/t9500-gitweb-standalone-no-errors.sh
index 46ba19b..07117a8 100755
--- a/t/t9500-gitweb-standalone-no-errors.sh
+++ b/t/t9500-gitweb-standalone-no-errors.sh
@@ -56,7 +56,7 @@
 	rm -f gitweb.log &&
 	perl -- "$TEST_DIRECTORY/../gitweb/gitweb.perl" \
 		>/dev/null 2>gitweb.log &&
-	if grep -q -s "^[[]" gitweb.log >/dev/null; then false; else true; fi
+	if grep "^[[]" gitweb.log >/dev/null 2>&1; then false; else true; fi
 
 	# gitweb.log is left for debugging
 }