improve Makefile for getting test-data

add a target for git and update docs

Author: kuk0

tests-and-benchmarks.markdown

@@ -13,10 +13,13 @@ you can clone from one of the following locations:
 * Git mirror repository:
   [github.com/bos/text-test-data](https://github.com/bos/text-test-data)
 
-You should clone that repository into the `tests` subdirectory (your
-clone must be named `text-test-data` locally), then run `make -C
-tests/text-test-data` to uncompress the test files.  Many tests and
-benchmarks will fail if the test files are missing.
+You can clone either repository into the `tests` subdirectory using
+
+    cd tests/
+    make text-test-data         # to clone from mercurial, OR
+    make VCS=git text-test-data # to clone from git
+
+Many tests and benchmarks will fail if the test files are missing.
 
 Functional tests
 ----------------

tests/Makefile

@@ -1,3 +1,4 @@
+VCS = hg
 count = 1000
 
 all: coverage literal-rule-test
@@ -12,7 +13,11 @@ build: text-test-data
 	cabal build
 
 text-test-data:
+ifeq ($(VCS),git)
+	git clone https://github.com/bos/text-test-data.git
+else
 	hg clone https://bitbucket.org/bos/text-test-data
+endif
 	$(MAKE) -C text-test-data
 
 coverage/text-tests.tix:
@@ -37,4 +42,4 @@ coverage/hpc_index.html: coverage/coverage.tix
 clean:
 	rm -rf dist coverage .hpc
 
-.PHONY: build coverage all literal-rule-test
+.PHONY: all build clean coverage literal-rule-test