[cxxmodules] Filter out source locations.

[vgvassilev]

If the declaration comes from an AST file no source locations are printed.

This patch is in the same direction as we took in 3a8dfca4

This is part of root-project/root#3850

[phsft-bot]

Starting build on ROOT-performance-centos7-multicore/default, ROOT-fedora27/noimt, ROOT-fedora29/python3, ROOT-ubuntu16/rtcxxmod, mac1014/cxx17, windows10/default
How to customize builds

[phsft-bot]

Build failed on windows10/default.
See console output.

Warnings:

• JENKINS-19022: warning: possible memory leak due to Git plugin usage; see: https://wiki.jenkins-ci.org/display/JENKINS/Remove+Git+Plugin+BuildsByBranch+BuildData
• CMake Warning at C:/build/workspace/roottest-pullrequests-build/rootspi/jenkins/root-build.cmake:879 (message):

[phsft-bot]

Build failed on ROOT-ubuntu16/rtcxxmod.
See console output.

Warnings:

• JENKINS-19022: warning: possible memory leak due to Git plugin usage; see: https://wiki.jenkins-ci.org/display/JENKINS/Remove+Git+Plugin+BuildsByBranch+BuildData
• CMake Warning at /mnt/build/workspace/roottest-pullrequests-build/rootspi/jenkins/root-build.cmake:879 (message):

Failing tests:

• projectroot.roottest.cling.template.separateDict.roottest_cling_template_separateDict_make
• projectroot.roottest.root.io.interface.roottest_root_io_interface_make
• projectroot.roottest.root.meta.evolution.roottest_root_meta_evolution_execCheckSum
• projectroot.roottest.root.tree.selectorreader.roottest_root_tree_selectorreader_make
• projectroot.roottest.root.tree.selector.roottest_root_tree_selector_make
• projectroot.roottest.cling.template.roottest_cling_template_runtemplatefriend

[vgvassilev]

@phsft-bot build just on ROOT-ubuntu16/rtcxxmod with flags -DCTEST_TEST_EXCLUDE_NONE=On

[phsft-bot]

Starting build on ROOT-ubuntu16/rtcxxmod with flags -DCTEST_TEST_EXCLUDE_NONE=On
How to customize builds

[phsft-bot]

Build failed on ROOT-ubuntu16/rtcxxmod.
See console output.

Warnings:

• JENKINS-19022: warning: possible memory leak due to Git plugin usage; see: https://wiki.jenkins-ci.org/display/JENKINS/Remove+Git+Plugin+BuildsByBranch+BuildData
• CMake Warning at /mnt/build/workspace/roottest-pullrequests-build/rootspi/jenkins/root-build.cmake:879 (message):

Failing tests:

• projectroot.runtutorials.tutorial_io_loopdir