gstvalue: preserve parse behaviour with warning

Preserve the previous behaviour where:
    name, val="5";
passed to gst_structure_from_string would have resulted in an int value,
rather than a string, despite the quote marks.

This will be changed to being interpreted as a string in the future, but
for the time being we will issue a warning about this to give users time
to fix their code to no longer rely on this bug.
27 jobs for clean_up_serialization in 51 minutes and 33 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Preparation
passed #1085900
gst indent

00:00:29

passed #1085899
manifest

00:00:29

 
  Build
passed #1085910
build cerbero cross-android universal

00:11:50

passed #1085914
gst-ios-13.2
build cerbero cross-ios universal

00:21:53

passed #1085911
build cerbero cross win32

00:08:01

passed #1085912
build cerbero cross win64

00:06:35

passed #1085909
build cerbero fedora x86_64

00:08:39

passed #1085913
gst-macos-10.15
build cerbero macos x86_64

00:09:32

passed #1085905
build clang fedora x86_64

00:09:15

passed #1085901
build fedora x86_64

00:08:25

passed #1085908
1809 windows docker
build msys2

00:32:43

passed #1085902
build nodebug fedora x86_64

00:07:28

passed #1085903
build static fedora x86_64

00:12:31

passed #1085904
build static nodebug fedora x86_64

00:07:59

passed #1085906
1809 windows docker
build vs2017 amd64

00:10:35

passed #1085907
1809 windows docker
build vs2017 x86

00:10:47

 
  Test
passed #1085915
gstreamer
check fedora

00:03:19

passed #1085916
gstreamer
integration testsuites fedora

00:42:35

passed #1085921
gstreamer
valgrind bad

00:09:15

passed #1085918
gstreamer
valgrind base

00:29:14

passed #1085917
gstreamer
valgrind core

00:15:43

passed #1085922
gstreamer
valgrind ges

00:07:59

passed #1085919
gstreamer
valgrind good

00:09:26

passed #1085920
gstreamer
valgrind ugly

00:01:49

 
  Integrate
passed #1085923
cross-android universal examples

00:10:45

passed #1085925
gst-ios-13.2
cross-ios universal examples

00:03:30

passed #1085924
documentation

00:05:19