tests: don't drop global hgrc

Various tests are failing when the simple store extension is loaded
because the test overrides HGRCPATH and preempts loading of extensions
that were injected via --extra-config-opt.

In most cases, it is acceptable to always load the global HGRCPATH.
So this commit changes a couple of tests so the global HGRCPATH
is still pulled in.

Differential Revision: https://phab.mercurial-scm.org/D3098

tests/test-command-template.t

@@ -284,7 +284,8 b' Test templates and style maps in files:'
 
  so it can be included in hgrc
 
-  $ cat <<'EOF' > myhgrc
+  $ cat <<EOF > myhgrc
+  > %include $HGRCPATH
   > %include map-simple
   > [templates]
   > foo = "{changeset}"

tests/test-wireproto.t

@@ -114,10 +114,7 b' HTTP without args-in-POST:'
 
 HTTP without the httpheader capability:
 
-  $ HGRCPATH="`pwd`/repo/.hgrc"
-  $ export HGRCPATH
-  $ CAP=httpheader
-  $ . "$TESTDIR/notcapable"
+  $ CAP=httpheader . "$TESTDIR/notcapable"
 
   $ hg serve -R repo -p $HGPORT2 -d --pid-file=hg2.pid -E error2.log -A access2.log
   $ cat hg2.pid >> $DAEMON_PIDS