msc_vlr_tests: fix rebuild: rebuild when src/ libs were rebuilt

Before this, a code change in libvlr or libmsc would not cause a rebuild of the
tests.

You'd have thought 'AM_LDADD' were the right name for the variable, but
apparently it is just 'LDADD' instead. Tested that it works as intended.

Change-Id: Icbdedc1581fa23abe9ed99cef3918592b25f30b3
1 file changed