info: add environment variable to enable append-mode debug log file

To enable persistent logging.
22 jobs for append_mode in 87 minutes and 13 seconds (queued for 67 minutes and 15 seconds)
Status Job ID Name Coverage
  Preparation
passed #484580
gst indent

00:00:33

passed #484579
manifest

00:00:45

 
  Build
passed #484586
build cerbero android universal

00:11:36

passed #484587
build cerbero cross win32

00:07:55

passed #484588
build cerbero cross win64

00:06:18

passed #484585
build cerbero fedora x86_64

00:05:54

manual #484590
gst-ios-12.2 allowed to fail manual
build cerbero ios universal
passed #484589
gst-macos-10.14
build cerbero macos x86_64

00:09:48

passed #484581
build fedora x86_64

00:06:14

passed #484582
build nodebug fedora x86_64

00:06:36

passed #484583
build static fedora x86_64

00:13:46

passed #484584
build static nodebug fedora x86_64

00:11:35

 
  Test
passed #484591
check fedora

00:04:27

passed #484592
integration testsuites fedora

00:24:27

passed #484597
valgrind bad

00:08:20

passed #484594
valgrind base

00:11:41

passed #484593
valgrind core

00:14:39

passed #484598
valgrind ges

00:09:07

passed #484595
valgrind good

00:10:21

passed #484596
valgrind ugly

00:02:16

 
  Integrate
passed #484599
android universal examples

00:12:29

passed #484600
documentation

00:04:01