logic: Fixed relative paths not working Code::Blocks project files (issue #663)

* Index non-target files if no others available

testing/project_setup/cxx_cbp/data/Test.cbp

@@ -73,6 +73,10 @@
 		<Unit filename="<source_path>/main.cpp">
 			<Option target="Test"/>
 		</Unit>
+		<Unit filename="src/test.cpp">
+			<Option target="Test"/>
+		</Unit>
+		<Unit filename="src/no_target.cpp" />
 		<Unit filename="<source_path>/CMakeLists.txt">
 			<Option virtualFolder="CMake Files\"/>
 		</Unit>

testing/project_setup/cxx_cbp/data/src/no_target.cpp

@@ -0,0 +1,4 @@
+void no_target()
+{
+	int b = 7;
+}

testing/project_setup/cxx_cbp/data/src/test.cpp

@@ -0,0 +1,4 @@
+void test()
+{
+	int a = 42;
+}