testing/testcase: ignore gfortran.so in ldd check

the rpath we set in LDFLAGS is not honored here, but we can ignore this
as rpath is needed on executables and not important on shared objects.

libgfortran.so is a shared object that happens to be executable, so it
appears in our ldd check, but we are not executing it directly so it
should be OK.

slapos/testing/testcase.py

@@ -200,9 +200,12 @@ def checkSoftware(slap, software_url):
       # nss is not a binary distribution, but for some reason it has invalid rpath, but it does
       # not seem to be a problem in our use cases.
       '*/parts/nss/*',
+      # npm packages containing binaries
       '*/node_modules/phantomjs*/*',
       '*/grafana/tools/phantomjs/*',
       '*/node_modules/puppeteer/*',
+      # gcc's gfortran runtime is linked against libz and ignores rpath
+      '*/libgfortran.so*',
       # left over of compilation failures
       '*/*__compile__/*',
   ))