Fix: put auto-detected Makefile path into a variable, but keep GIT_EXEC_PATH overrideable via Makefile command arguments.
Fix: put auto-detected Makefile path into a variable, but keep
GIT_EXEC_PATH overrideable via Makefile command arguments.

dhilgarth/gitflow,JelteF/gitflow,oddnoc/gitflow,yonglehou/gitflow-1