autoconf: tweaks to the check for --static-pcap-only support.

Use the -s and -q flags to suppress output from grep, rather than
directing the standard output and error to /dev/null; they've  been in
the Single UNIX Specification since at least UNIX 98.

Wrap "Checking..." and result messages around the test.

Author: guyharris

aclocal.m4

@@ -657,10 +657,13 @@ AC_DEFUN(AC_LBL_LIBPCAP,
             # statically linked, and provide only the direct
             # dependencies with --static-pcap-only.
             #
-            if grep "static-pcap-only" "$PCAP_CONFIG" >/dev/null 2>&1
+            AC_MSG_CHECKING([whether $PCAP_CONFIG supports --static-pcap-only])
+            if grep -s -q "static-pcap-only" "$PCAP_CONFIG"
             then
+                AC_MSG_RESULT([yes])
                 static_opt="--static-pcap-only"
             else
+                AC_MSG_RESULT([no])
                 static_opt="--static"
             fi
             $2="-I$local_pcap_dir $$2"