Backport the ability to set the ToS bits on Linux when not running as root.

Normally, we would not backport features into 1.4, but, I was convinced by the
justification supplied by the supplier of this patch.  He pointed out that this
patch removes a requirement for running as root, thus reducing the potential
impacts of security issues.

(closes issue #11742)
Reported by: paravoid
Patches:
      libcap.diff uploaded by paravoid (license 200)


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@98265 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configure.ac

@@ -174,6 +174,7 @@ AC_SUBST(AST_DEVMODE)
 
 AST_EXT_LIB_SETUP([ALSA], [Advanced Linux Sound Architecture], [asound])
 AST_EXT_LIB_SETUP([CURL], [cURL], [curl])
+AST_EXT_LIB_SETUP([CAP], [POSIX 1.e capabilities], [cap])
 AST_EXT_LIB_SETUP([CURSES], [curses], [curses])
 AST_EXT_LIB_SETUP([GNUTLS], [GNU TLS support (used for iksemel only)], [gnutls])
 AST_EXT_LIB_SETUP([GSM], [GSM], [gsm], [, or 'internal'])
@@ -398,6 +399,10 @@ AST_EXT_LIB_CHECK([ALSA], [asound], [snd_spcm_init], [alsa/asoundlib.h], [-lm -l
 
 AST_EXT_LIB_CHECK([CURSES], [curses], [initscr], [curses.h])
 
+if test "x${host_os}" = "xlinux-gnu" ; then
+  AST_EXT_LIB_CHECK([CAP], [cap], [cap_from_text], [sys/capability.h])
+fi
+
 GSM_INTERNAL="yes"
 AC_SUBST(GSM_INTERNAL)
 GSM_SYSTEM="yes"