Bug 1432395 - Add valgrind suppressions for system libraries on Debian. r=njn

The first two are variants of existing ones, with a slightly different
signature, and tha last one is well known and found in glib-related
suppression files like https://github.com/flatpak/flatpak/blob/master/tests/glib.supp

--HG--
extra : rebase_source : 2a209cc5987405e7ff638bbf69e1b74202b0357e

build/valgrind/x86_64-pc-linux-gnu.sup

@@ -29,6 +29,14 @@
    fun:FcPatternObjectInsertElt
    ...
 }
+{
+   Bug 1187649
+   Memcheck:Leak
+   match-leak-kinds: definite
+   fun:malloc
+   fun:FcPatternObjectInsertElt
+   ...
+}
 # With older versions of fontconfig (e.g. 2.8.0 on taskcluster systems),
 # there's an uninitialized memory usage and leak when loading app fonts.
 {
@@ -53,6 +61,18 @@
    fun:FcConfigAppFontAddDir
    ...
 }
+{
+   Bug 1231701
+   Memcheck:Leak
+   match-leak-kinds: definite
+   fun:malloc
+   fun:FcDirScanConfig
+   fun:FcDirScanConfig
+   fun:FcDirCacheScan
+   fun:FcConfigAddDirList
+   fun:FcConfigAppFontAddDir
+   ...
+}
 # Leaks due to either Gtk+3 or cairo, but Gecko is not directly involved with
 # those cairo interactions.  One suspected cause is Gecko not closing the
 # display to work around a bug in old Gtk+3 versions.  See also bug 1228724.
@@ -162,6 +182,15 @@
    fun:gdk_display_open
    ...
 }
+{
+  _g_io_module_get_default
+   Memcheck:Leak
+   ...
+   fun:g_io_module_new
+   fun:g_io_modules_scan_all_in_directory_with_scope
+   fun:_g_io_modules_ensure_loaded
+   fun:_g_io_module_get_default
+}
 
 ###################################
 #  Leaks in short lived precesses #