Allow setting VERSION_GIT

Fixes: #79

CMakeLists.txt

@@ -6,14 +6,23 @@ set (tini_VERSION_MAJOR 0)
 set (tini_VERSION_MINOR 14)
 set (tini_VERSION_PATCH 0)
 
+set (GIT_PREFIX " - git.")
+
 # Build options
 option(MINIMAL "Disable argument parsing and verbose output" OFF)
 
+# Set VERSION_GIT to INTERNAL so it does not persist across runs of CMake, just
+# like the auto-discovery would.
+set(VERSION_GIT "" CACHE INTERNAL "Override the git revision")
+
 if(MINIMAL)
 	add_definitions(-DTINI_MINIMAL=1)
 endif()
 
 # Extract git version and dirty-ness
+if(VERSION_GIT)
+	set(tini_VERSION_GIT "${GIT_PREFIX}${VERSION_GIT}")
+else()
 	execute_process (
 	  COMMAND git --git-dir "${PROJECT_SOURCE_DIR}/.git" --work-tree "${PROJECT_SOURCE_DIR}" log -n 1 --date=local --pretty=format:%h
 	  WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}"
@@ -28,13 +37,14 @@ execute_process(
 	)
 
 	if("${git_version_check_ret}" EQUAL 0)
-  set(tini_VERSION_GIT " - git.${tini_VERSION_GIT}")
+		set(tini_VERSION_GIT "${GIT_PREFIX}${tini_VERSION_GIT}")
 		if(NOT "${git_dirty_check_out}" STREQUAL "")
 			set(tini_VERSION_GIT "${tini_VERSION_GIT}-dirty")
 		endif()
 	else()
 		set(tini_VERSION_GIT "")
 	endif()
+endif()
 
 # Flags
 include(CheckCSourceCompiles)