ftmod_libpri: Initial support for BRI and various cleanups + double locking fix

Fixes:
- Fix double locking in check_state(): remove ftdm_mutex_(un)lock calls.

New:
- Add lpwrap_init_bri() to initialize libpri in BRI mode
- Use trunk type to determine PRI/BRI and PTP/PTMP mode (no additional configuration required).
- Improve libpri detection code in configure.ac, check whether libpri is usable
  and if BRI support is available (needs more work)

Cleanups:
- Whitespace and indentation cleanups
- Rename str2* functions to parse_*
- Simplify libpri_configure_span() option parsing and bail out on error
- Add "ftdm libpri help" command that displays usage information
- Coding style cleanups and other (minor) changes

Known issues:
- BRI PTMP TE Q.921 link does not go beyond TEI ASSIGNED state,
  SABME requests are ignored by NT (EuroISDN DTAG, DAHDI-2.3.0.1, vzaphfc)

Signed-off-by: Stefan Knoblich <s.knoblich@axsentis.de>

libs/freetdm/configure.ac

@@ -144,21 +144,6 @@ fi
 ##
 AC_MSG_RESULT([${as_nl}<<>> Modules and optional features])
 
-##
-# libpri (TODO: add checks)
-#
-HAVE_LIBPRI="no"
-AC_ARG_WITH([libpri],
-	[AS_HELP_STRING([--with-libpri], [Install ftmod_libpri])],
-	[case "${withval}" in
-	 no)	enable_libpri="no" ;;
-	 *)	enable_libpri="yes" ;;
-	 esac],
-	[enable_libpri="no"]
-)
-HAVE_LIBPRI="${enable_libpri}"
-AM_CONDITIONAL([HAVE_LIBPRI],[test "${enable_libpri}" = "yes"])
-
 ##
 # pritap (TODO: add checks)
 #
@@ -193,6 +178,50 @@ AC_CHECK_LIB([openr2], [openr2_context_set_io_type], [HAVE_OPENR2="yes"])
 AC_MSG_RESULT([checking whether to build ftmod_r2... ${HAVE_OPENR2}])
 AM_CONDITIONAL([HAVE_OPENR2], [test "${HAVE_OPENR2}" = "yes"])
 
+##
+# Digium libpri (TODO: add checks)
+#
+HAVE_LIBPRI="no"
+AC_ARG_WITH([libpri],
+	[AS_HELP_STRING([--with-libpri], [Install ftmod_libpri])],
+	[case "${withval}" in
+	 no)	enable_libpri="no" ;;
+	 *)	enable_libpri="yes" ;;
+	 esac],
+	[enable_libpri="no"]
+)
+if test "${enable_libpri}" != "no"
+then
+	AC_MSG_RESULT([${as_nl}<<>> Digium libpri])
+
+	save_LIBS="${LIBS}"
+	LIBS="${LIBS} -lpri"
+	AC_MSG_CHECKING([whether libpri is usable])
+	AC_LINK_IFELSE(
+		[AC_LANG_PROGRAM(
+			[#include <libpri.h>],
+			[const char *version = pri_get_version();]
+		)],
+		[AC_MSG_RESULT([yes])],
+		[AC_MSG_RESULT([no])
+		 AC_MSG_ERROR([libpri is not installed or unusable (see config.log for details)])]
+	)
+
+	AC_MSG_CHECKING([whether libpri has BRI support])
+	AC_LINK_IFELSE(
+		[AC_LANG_PROGRAM(
+			[extern void pri_new_bri_cb(void);],
+			[pri_new_bri_cb();]
+		)],
+		[AC_DEFINE([HAVE_LIBPRI_BRI], [1], [libpri has bri support])
+		 AC_MSG_RESULT([yes])],
+		[AC_MSG_RESULT([no])]
+	)
+	LIBS="${save_LIBS}"
+fi
+HAVE_LIBPRI="${enable_libpri}"
+AM_CONDITIONAL([HAVE_LIBPRI],[test "${enable_libpri}" = "yes"])
+
 ##
 # Sangoma Wanpipe
 #