Add suppression for "uninitialized memory" error in getaddrinfo.

tools_webrtc/valgrind/memcheck/suppressions.txt

 # This file is used in addition to the one already maintained in Chrome.
 # It acts as a place holder for future additions for WebRTC.
 # It must exist for the Python wrapper script to work properly.
 
 # There are three kinds of suppressions in this file.
 # 1. third_party libraries
 # 2. webrtc stuff
 # 3. libjingle stuff (talk folder)
 #-----------------------------------------------------------------------
 
 # third_party libraries
 
 {
    libc_free_hitting_gce_vms
    Memcheck:Free
    fun:free
    fun:__libc_freeres
    fun:_vgnU_freeres
    ...
 }
 {
    Ubuntu_Precise_Itoa_Optimized_Code
    Memcheck:Uninitialized
    fun:_itoa_word
    fun:vfprintf
    fun:vsnprintf
    fun:snprintf
    ...
 }
+# See: https://bugs.chromium.org/p/webrtc/issues/detail?id=7973
+{
+   libc_getaddrinfo_uninitialized
+   Memcheck:Param
+   sendmsg(mmsg[0].msg_hdr)
+   fun:sendmmsg
+   fun:__libc_res_nsend
+   fun:__libc_res_nquery
+   fun:__libc_res_nsearch
+   fun:_nss_dns_gethostbyname4_r
+   fun:gaih_inet
+   fun:getaddrinfo
+   ...
+}
 
 #-----------------------------------------------------------------------
 # webrtc stuff
 
 {
    bug_6784
    Memcheck:Leak
    fun:_Znw*
    fun:_ZN3rtc10HttpServer16HandleConnectionEPNS_15StreamInterfaceE
    fun:_ZN3rtc12_GLOBAL__N_122CreateClientConnectionERNS_10HttpServerERNS0_17HttpServerMonitorEb
@@ skipping 428 matching lines @@
 {
    bug_687087
    Memcheck:Uninitialized
    fun:vfprintf
    fun:vsnprintf
    fun:snprintf
    ...
    fun:_ZNK6webrtc11MockRtpRtcp11FlexfecSsrcEv
    ...
 }