baseparse: Don't ignore repeated incoming PTS

If the input stream has PTS set, then previously baseparse
would only take a new timestamp when it changes, but it's
not clear why it does that.

When parsing video streams this behaviour makes it lose
timestamps from incoming video frames if there are duplicates
due to upstream timestamping problems.
Status Job ID Name Coverage
  Preparation
passed #626386
gst indent

00:00:31

passed #626385
manifest

00:00:43

 
  Build
passed #626396
build cerbero cross-android universal

00:12:08

manual #626400
gst-ios-12.2 allowed to fail manual
build cerbero cross-ios universal
passed #626397
build cerbero cross win32

00:10:45

passed #626398
build cerbero cross win64

00:06:36

passed #626395
build cerbero fedora x86_64

00:10:39

passed #626399
gst-macos-10.14
build cerbero macos x86_64

00:07:52

passed #626391
build clang fedora x86_64

00:10:43

passed #626387
build fedora x86_64

00:10:01

passed #626394
docker windows 1607
build msys2

00:12:24

passed #626388
build nodebug fedora x86_64

00:09:09

passed #626389
build static fedora x86_64

00:14:02

passed #626390
build static nodebug fedora x86_64

00:07:36

passed #626392
docker windows 1607
build vs2017 amd64

00:10:09

passed #626393
docker windows 1607
build vs2017 x86

00:10:46

 
  Test
passed #626401
check fedora

00:04:37

failed #631126
integration testsuites fedora

00:17:02

passed #626407
valgrind bad

00:06:17

passed #626404
valgrind base

00:11:21

passed #626403
valgrind core

00:12:18

passed #626408
valgrind ges

00:09:36

passed #626405
valgrind good

00:27:04

passed #626406
valgrind ugly

00:02:31

failed #626402
integration testsuites fedora

00:19:47

 
  Integrate
passed #626409
cross-android universal examples

00:06:36

skipped #626411
gst-ios-12.2 allowed to fail manual
cross-ios universal examples
passed #626410
documentation

00:04:04

 
Name Stage Failure
failed
integration testsuites fedora Test
           Total: 1451
Uploading artifacts...
gst-build/build/meson-logs/: found 2 matching files
validate-logs: found 69918 matching files

Uploading artifacts to coordinator... ok
id=631126 responseStatus=201 Created token=-QVUiSqc
Uploading artifacts...
validate-logs/*.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=631126 responseStatus=201 Created token=-QVUiSqc
ERROR: Job failed: exit code 1