Remove unnecessary reference to $SRCDIR in Buck genrules

In new buck version `$SRCDIR` is not necessary any more.  Buck now
always runs genrule relative to the $SRCDIR link forest.

Change-Id: Iee88bb575c7baa62bc087527927be5347a7f8f95
diff --git a/java_doc.bucklet b/java_doc.bucklet
index 69df603..1a0a240 100644
--- a/java_doc.bucklet
+++ b/java_doc.bucklet
@@ -33,8 +33,13 @@
     paths,
     srcs = [],
     deps = [],
-    visibility = []
+    visibility = [],
+    do_it_wrong = False,
   ):
+  if do_it_wrong:
+    sourcepath = paths
+  else:
+    sourcepath = ['$SRCDIR/' + n for n in paths]
   genrule(
     name = name,
     cmd = ' '.join([
@@ -49,7 +54,7 @@
       '-link http://docs.oracle.com/javase/7/docs/api',
       '-subpackages ' + pkg,
       '-sourcepath ',
-      ':'.join([n for n in paths]),
+      ':'.join(sourcepath),
       ' -classpath ',
       ':'.join(['$(location %s)' % n for n in deps]),
       '-d $TMP',