make 'make check' work with non-installed prefix builds

add the appropriate environment to the command lines

Change-Id: Ic9d3c60255be88f431213acd8c5e0ff55e014f5b
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

mkspecs/features/testcase.prf

@@ -36,6 +36,9 @@ else:           check.commands += $(DESTDIR_TARGET)
 # Allow for custom arguments to tests
 check.commands += $(TESTARGS)
 
+# Add environment for non-installed builds
+qtAddTargetEnv(check.commands)
+
 # If the test is marked as insignificant, discard the exit code
 insignificant_test:check.commands = -$${check.commands}