Integrate gcov support into Qt build system.

To instrument a Qt application or library with the gcov coverage
tool, do `CONFIG+=gcov' in the application .pro file.

To instrument Qt itself with gcov, use the `-gcov' configure
option.

Change-Id: If24e91d95318609b0df1a76ed6d679bd92bcaab2
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>

.gitignore

@@ -61,6 +61,8 @@ Makefile*
 *.pro.user*
 *.qmlproject.user*
 *.gcov
+*.gcda
+*.gcno
 bin/Qt*.dll
 bin/assistant*
 bin/designer*

configure

@@ -1518,6 +1518,11 @@ while [ "$#" -gt 0 ]; do
             QTCONFIG_CONFIG="$QTCONFIG_CONFIG testcocoon"
         fi
         ;;
+    gcov)
+        if [ "$VAL" = "yes" ]; then
+            QTCONFIG_CONFIG="$QTCONFIG_CONFIG gcov"
+        fi
+        ;;
     platform)
         PLATFORM="$VAL"
         # keep compatibility with old platform names
@@ -3438,6 +3443,7 @@ Configure options:
     -qtlibinfix <infix>  Renames all libQt*.so to libQt*<infix>.so.
 
     -testcocoon ........ Instrument Qt with the TestCocoon code coverage tool.
+    -gcov .............. Instrument Qt with the GCov code coverage tool.
 
     -D <string> ........ Add an explicit define to the preprocessor.
     -I <string> ........ Add an explicit include path.

mkspecs/features/gcov.prf

@@ -0,0 +1,31 @@
+#
+#    Tested with gcov 4.8.1
+#    http://gcc.gnu.org/onlinedocs/gcc-4.8.1/gcc/Gcov.html
+
+# To instrument a Qt application or library with the gcov coverage
+# tool, do `CONFIG+=gcov' in the application .pro file.
+#
+# To instrument Qt itself with gcov, use the `-gcov' configure
+# option.
+
+# The .gcno file is generated when the source file is compiled.
+# The .gcda file is generated when a program is executed.
+
+# Example how to generate the html output after you've run the program or test
+#
+# lcov --capture --directory . --output-file coverage-gcov.info --no-external
+# lcov --output-file coverage-gcov.info --remove coverage-gcov.info '*.moc*' '.*rcc*' '*3rdparty*'
+# genhtml coverage-gcov.info --output-directory doc/coverage
+
+# If you want to use gcov directly, you most likely need to manually move the .gcda and .gcno files
+# along with the program.
+#
+# mv .obj/debug-shared/tst_example.gc* .
+# gcov -b -c tst_example.cpp
+
+QMAKE_CFLAGS           += -fprofile-arcs -ftest-coverage
+QMAKE_CXXFLAGS         += -fprofile-arcs -ftest-coverage
+QMAKE_OBJECTIVE_CFLAGS += -fprofile-arcs -ftest-coverage
+QMAKE_LFLAGS           += -fprofile-arcs -ftest-coverage
+
+QMAKE_CLEAN += $(OBJECTS_DIR)*.gcno and $(OBJECTS_DIR)*.gcda