travis: use a valgrind suppressions file

We don't care about the supposed zlib errors, and the leak from
giterr_set isn't interesting, as it gets freed each time an error is
set.

Give valgrind a suppressions file so it doesn't tell us about them.

.travis.yml

@@ -32,7 +32,7 @@ script:
 # Run Tests
 after_script:
  - ctest -V .
- - if [ -f ./libgit2_clar ]; then valgrind --leak-check=full --show-reachable=yes ./libgit2_clar; else echo "Skipping valgrind"; fi
+ - if [ -f ./libgit2_clar ]; then valgrind --leak-check=full --show-reachable=yes --suppressions=../libgit2_clar.supp ./libgit2_clar; else echo "Skipping valgrind"; fi
 
 # Only watch the development branch
 branches:

libgit2_clar.supp

@@ -0,0 +1,12 @@
+{
+        ignore-zlib-errors-cond
+        Memcheck:Cond
+        obj:*libz.so*
+}
+
+{
+        ignore-giterr-set-leak
+        Memcheck:Leak
+        ...
+        fun:giterr_set
+}