Support gathering of code coverage data for RPC tests

The RPC tests (via `qa/pull-tester/rpc-tests.py`) are now executed,
when gathering code coverage data, for example with `make cov`.

Generating coverage data requires `lcov`, which can installed with:

    sudo apt-get install lcov

To also use the BitcoinJ tests, get the test tool:

    TOOL_URL=https://github.com/theuni/bitcoind-comparisontool/raw/master/pull-tests-8c6666f.jar
    TOOL_HASH=a865332b3827abcde684ab79f5f43c083b0b6a4c97ff5508c79f29fee24f11cd
    wget $TOOL_URL -O ./share/BitcoindComparisonTool.jar
    echo "$TOOL_HASH  ./share/BitcoindComparisonTool.jar" | shasum --algorithm 256 --check

The coverage data can be generated with:

    ./autogen.sh
    ./configure --enable-lcov --with-comparison-tool=./share/BitcoindComparisonTool.jar
    make
    make cov

Optionally the options `--enable-extended-rpc-tests` and
`--enable-comparison-tool-reorg-tests` may be used to enable more time
consuming tests.

It then runs the tests and generates two HTML reports:

 - test_bitcoin.coverage/index.html
 - total.coverage/index.html

Makefile.am

@@ -39,7 +39,7 @@ OSX_PACKAGING = $(OSX_DEPLOY_SCRIPT) $(OSX_FANCY_PLIST) $(OSX_INSTALLER_ICONS) $
 
 COVERAGE_INFO = baseline_filtered_combined.info baseline.info block_test.info \
   leveldb_baseline.info test_bitcoin_filtered.info total_coverage.info \
-  baseline_filtered.info block_test_filtered.info \
+  baseline_filtered.info block_test_filtered.info rpc_test.info rpc_test_filtered.info \
   leveldb_baseline_filtered.info test_bitcoin_coverage.info test_bitcoin.info
 
 dist-hook:
@@ -178,11 +178,20 @@ block_test.info: test_bitcoin_filtered.info
 block_test_filtered.info: block_test.info
 	$(LCOV) -r $< "/usr/include/*" -o $@
 
+rpc_test.info: test_bitcoin_filtered.info
+	-@TIMEOUT=15 python qa/pull-tester/rpc-tests.py $(EXTENDED_RPC_TESTS)
+	$(LCOV) -c -d $(abs_builddir)/src --t rpc-tests -o $@
+	$(LCOV) -z -d $(abs_builddir)/src
+	$(LCOV) -z -d $(abs_builddir)/src/leveldb
+
+rpc_test_filtered.info: rpc_test.info
+	$(LCOV) -r $< "/usr/include/*" -o $@
+
 test_bitcoin_coverage.info: baseline_filtered_combined.info test_bitcoin_filtered.info
 	$(LCOV) -a baseline_filtered.info -a leveldb_baseline_filtered.info -a test_bitcoin_filtered.info -o $@
 
-total_coverage.info:  baseline_filtered_combined.info test_bitcoin_filtered.info block_test_filtered.info
-	$(LCOV) -a baseline_filtered.info -a leveldb_baseline_filtered.info -a test_bitcoin_filtered.info -a block_test_filtered.info -o $@ | $(GREP) "\%" | $(AWK) '{ print substr($$3,2,50) "/" $$5 }' > coverage_percent.txt
+total_coverage.info: baseline_filtered_combined.info test_bitcoin_filtered.info block_test_filtered.info rpc_test_filtered.info
+	$(LCOV) -a baseline_filtered.info -a leveldb_baseline_filtered.info -a test_bitcoin_filtered.info -a block_test_filtered.info -a rpc_test_filtered.info -o $@ | $(GREP) "\%" | $(AWK) '{ print substr($$3,2,50) "/" $$5 }' > coverage_percent.txt
 
 test_bitcoin.coverage/.dirstamp:  test_bitcoin_coverage.info
 	$(GENHTML) -s $< -o $(@D)