Fix flaky construction of genrule $SRCDIR

When the project root is initialized to "." the absolute paths for
genrule() srcs can be constructed as /Users/self/src/./path.  This
later confuses genrule when it looks for the prefix to strip when
creating the $SRCDIR, the canonical path of a source never contains
/./ as a component.
diff --git a/src/com/facebook/buck/cli/ b/src/com/facebook/buck/cli/
index 2e5ad60..41b192f 100644
--- a/src/com/facebook/buck/cli/
+++ b/src/com/facebook/buck/cli/
@@ -333,7 +333,7 @@
   public static void main(String[] args) {
     Main main = new Main(System.out, System.err);
-    File projectRoot = new File(".");
+    File projectRoot = new File("").getAbsoluteFile();
     int exitCode = FAIL_EXIT_CODE;
     try {
       exitCode = main.tryRunMainWithExitCode(projectRoot, args);