FS_POSIX.runInShell(): on MacOS use a login shell

On Mac, $PATH for UI programs is not the same as in a shell (terminal).
It is typically much shorter. This may lead to surprises when hooks that
work fine via the command-line git do not work when run via JGit in a UI
application, such as EGit in Eclipse.

Therefore use a login shell to run hooks and other commands spawned by
git if we're on MacOS. This will give the hooks the same environment as
in a terminal.

Bug: egit-16
Change-Id: Id2e5485c6d3080d3ef8baa61ad7f6f198f77c590
Signed-off-by: Thomas Wolf <twolf@apache.org>

org.eclipse.jgit/src/org/eclipse/jgit/util/FS_POSIX.java

@@ -250,8 +250,12 @@ private static void apply(Set<PosixFilePermission> set,
 	/** {@inheritDoc} */
 	@Override
 	public ProcessBuilder runInShell(String cmd, String[] args) {
-		List<String> argv = new ArrayList<>(4 + args.length);
+		List<String> argv = new ArrayList<>(5 + args.length);
 		argv.add("sh"); //$NON-NLS-1$
+		if (SystemReader.getInstance().isMacOS()) {
+			// Use a login shell to get the full normal $PATH
+			argv.add("-l"); //$NON-NLS-1$
+		}
 		argv.add("-c"); //$NON-NLS-1$
 		argv.add(cmd + " \"$@\""); //$NON-NLS-1$
 		argv.add(cmd);