Allow test suite runner to come from a different repo

Makefile.am

@@ -5,6 +5,8 @@
 
 EXTRA_DIST = Changes ReadMe.md License CMakeLists.txt doc/doxygen.cfg
 
+LIBYAML_TEST_SUITE_RUN_REPO_DEFAULT := https://github.com/yaml/libyaml
+LIBYAML_TEST_SUITE_RUN_REPO ?= $(LIBYAML_TEST_SUITE_RUN_REPO_DEFAULT)
 LIBYAML_TEST_SUITE_RUN_BRANCH ?= run-test-suite
 
 pkgconfigdir = $(libdir)/pkgconfig
@@ -33,6 +35,7 @@
 test-all: test test-suite
 
 tests/run-test-suite:
+ifeq ($(LIBYAML_TEST_SUITE_RUN_REPO),$(LIBYAML_TEST_SUITE_RUN_REPO_DEFAULT))
 	  -git branch --track $(LIBYAML_TEST_SUITE_RUN_BRANCH) origin/$(LIBYAML_TEST_SUITE_RUN_BRANCH)
 	  -git worktree prune
 	  git worktree add $@ $(LIBYAML_TEST_SUITE_RUN_BRANCH)
@@ -36,6 +39,9 @@
 	  -git branch --track $(LIBYAML_TEST_SUITE_RUN_BRANCH) origin/$(LIBYAML_TEST_SUITE_RUN_BRANCH)
 	  -git worktree prune
 	  git worktree add $@ $(LIBYAML_TEST_SUITE_RUN_BRANCH)
+    else
+	  git clone --branch $(LIBYAML_TEST_SUITE_RUN_BRANCH) $(LIBYAML_TEST_SUITE_RUN_REPO) $@
+    endif
 
 packaging:
 	-git branch --track $@ origin/$@