rdmd: Clean up the temporary executable file if the build fails

OPTLINK may leave behind a broken executable, although the build failed.
Depending on user options, this .tmp file may reside outside the
rdmd work directory, so clean it up if it is created.
Merge pull request #110 from CyberShadow/rdmd-20140127

rdmd: Clean up the temporary executable file if the build fails
rdmd: Use execv on supported systems
Merge pull request #112 from CyberShadow/rdmd-20140201

rdmd: Use execv on supported systems
rdmd: Fix --dry-run
rdmd_test: Add test for issue 11983
Merge pull request #113 from CyberShadow/rdmd-20140202

rdmd: Fix `--dry-run`, add test for issue 11983
Fix #12149: ".exe" not auto-added with -of on windows.
Merge pull request #114 from Abscissa/master

Fix #12149: ".exe" not auto-added with -of on windows.
Add test-case for Issue 12149 - RDMD -of switch doesn't append .exe to an executable on Windows.
Merge pull request #116 from AndrejMitrovic/Test12149

Add test-case for Issue 12149 - RDMD -of switch doesn't append .exe to an executable on Windows.