coverity: compile tests, but not execute them

Compiling unit tests would allow Coverity to analyze them too and thus
find more bugs.  The problem is that binaries listed in check_PROGRAMS
are not compiled during 'make all', but only during 'make check'.

One approach [1] is to run 'make check' in do_build(), however it breaks
'Coverity-Upload' job because some unit tests are failing.  This is why
I had to revert bf84ba9f69 together with
ae41942214 that was supposed to fix it.

Even if all unit tests were passing, we still don't want to execute them
because running tests is beyond the scope of 'Coverity-Upload' job.

Another approach is to patch Makefile.am files replacing check_PROGRAMS
with noinst_PROGRAMS, so that the test binaries are compiled during
'make all' but not executed.

Change-Id: Idf0714a59356633021be21acc47f9471d059b7fe
Related: [1] I3f3149a61df96646798c72d0ad31c41b97e6b81f

coverity/prepare_source_Osmocom.sh

@@ -47,6 +47,13 @@ for proj in \
 	else
 		git clone git://git.osmocom.org/$proj
 	fi
+
+	# We want to compile tests, but not execute them.  Using 'noinst_PROGRAMS'
+	# instead of 'check_PROGRAMS' allows building test binaries during 'make all'.
+	files="$(git -C $proj grep -l check_PROGRAMS)"
+	if [ -n "$files" ]; then
+		sed -i "s/check_PROGRAMS/noinst_PROGRAMS/" $files
+	fi
 done
 
 if ! [ -d layer1-api ]; then