Fix bootstrap on windows

Likely a better way todo this but the colons in windows file paths mess
up the tar command so that nothing could be extracted. This got the
bootstrap command going on my windows system.
14 jobs for windows-mingw-tar in 50 minutes and 41 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #375349
manifest

00:00:37

 
  Pre Build
passed #375351
cerbero deps android universal

00:50:03

passed #375350
cerbero deps fedora x86_64

00:33:58

failed #375355
gst-ios-12.2
cerbero deps ios universal

00:00:38

failed #375354
gst-macos-10.14
cerbero deps macos x86_64

00:00:41

passed #375352
cerbero deps windows x86

00:44:34

passed #375353
cerbero deps windows x86_64

00:47:10

 
  Build
skipped #375357
cerbero android universal
skipped #375358
cerbero cross win32
skipped #375359
cerbero cross win64
skipped #375356
cerbero fedora x86_64
skipped #375361
gst-ios-12.2
cerbero ios universal
skipped #375360
gst-macos-10.14
cerbero macos x86_64
 
  Integrate
skipped #375362
cerbero android universal examples
 
Name Stage Failure
failed
cerbero deps macos x86_64 Pre Build
0:00:01 Recipe 'm4' failed at the build step 'extract'

Unpacking /Users/gst-ci/builds/raytiley/cerbero/cerbero-sources/m4-1.4.18/m4-1.4.18.tar.xz in /Users/gst-ci/builds/raytiley/cerbero/cerbero-build/sources/build-tools

Uploading artifacts...
Runtime platform arch=amd64 os=darwin pid=2080 revision=ac2a293c version=11.11.2
manifest.xml: found 1 matching files

cerbero-build/logs: found 16 matching files

WARNING: cerbero-build/cerbero-deps.log: no matching files
WARNING: cerbero-deps.tar.gz: no matching files
failed
cerbero deps ios universal Pre Build

Uploading artifacts...
Runtime platform arch=amd64 os=darwin pid=2284 revision=ac2a293c version=11.11.2
manifest.xml: found 1 matching files

cerbero-build/logs: found 22 matching files

WARNING: cerbero-build/cerbero-deps.log: no matching files
WARNING: cerbero-deps.tar.gz: no matching files
Uploading artifacts to coordinator... ok
id=375355 responseStatus=201 Created token=JGiHeATt
ERROR: Job failed: Process exited with: 1. Reason was: ()