AppVeyor|Travis: Re-introduce clone depth

Depth 1 made surpassed pushed fail so it was dropped.
No depth limit wastes time and hardware resources though, and
has some risk that depth 1 will be re-introduced, by mistake.
So let's try 50 now.

Related commits:
- 10c2354588 — AppVeyor
- 88cf657da9 — Travis

.travis.yml

@@ -12,6 +12,9 @@ dist: trusty
 # https://github.com/travis-ci/travis-ci/issues/9033
 sudo: required
 
+git:
+  depth: 50
+
 env:
   global:
     - CFLAGS='-g -pipe'

appveyor.yml

@@ -36,6 +36,9 @@ init:
 # version format
 version: libexpat-{build}
 
+# set clone depth, clone entire repository history if not defined
+clone_depth: 50
+
 # clone directory
 clone_folder: c:\projects\libexpat