Fix free_all_mem and EXITFREE definition

Because of the '$' in `if(DEFINED $ENV{VALGRIND_CHECK})` EXITFREE wasn't being
defined, so the `free_all_mem` wasn't being included or called in the resulting
binary.

This commit fixes that, and also adds includes needed for `free_all_mem`
compilation.

.gitignore

@@ -22,6 +22,7 @@
 /src/testdir/tiny.vim
 /src/testdir/test*.out
 /src/testdir/test.log
+/src/testdir/viminfo
 /src/testdir/test.ok
 /src/testdir/*.failed
 /src/testdir/X*