libpjsip: security bump to 2.7.2

Fixes the following vulnerabilities:

- CVE-2018-1000098: Crash when parsing SDP with an invalid media format
  description

- CVE-2018-1000099: Crash when receiving SDP with invalid fmtp attribute

[Peter: add CVE info]
Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit ed0d9d6f36dfc3e99ee70cc34de0c380925e871f)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libpjsip/libpjsip.hash

@@ -1,6 +1,6 @@
-# From http://www.pjsip.org/release/2.7.1/MD5SUM.TXT
-md5	99a64110fa5c2debff40e0e8d4676380  pjproject-2.7.1.tar.bz2
+# From http://www.pjsip.org/release/2.7.2/MD5SUM.TXT
+md5	fa3f0bc098c4bff48ddd92db1c016a7a  pjproject-2.7.2.tar.bz2
 
 # Locally computed
-sha256	59fabc62a02b2b80857297cfb10e2c68c473f4a0acc6e848cfefe8421f2c3126	pjproject-2.7.1.tar.bz2
+sha256	9c2c828abab7626edf18e04b041ef274bfaa86f99adf2c25ff56f1509e813772	pjproject-2.7.2.tar.bz2
 sha256	8177f97513213526df2cf6184d8ff986c675afb514d4e68a404010521b880643	COPYING

package/libpjsip/libpjsip.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBPJSIP_VERSION = 2.7.1
+LIBPJSIP_VERSION = 2.7.2
 LIBPJSIP_SOURCE = pjproject-$(LIBPJSIP_VERSION).tar.bz2
 LIBPJSIP_SITE = http://www.pjsip.org/release/$(LIBPJSIP_VERSION)
 LIBPJSIP_DEPENDENCIES = libsrtp