Fix a nullness warning.

This silences a warning null pointer passed as an argument to a
'nonnull' parameter

BUG=None
Test: The warning is gone.

Change-Id: I10a17d4674bfb373d7fe8666863abd5f10a4d11f

tools/zipalign/ZipEntry.cpp

@@ -130,6 +130,7 @@ void ZipEntry::initNew(const char* fileName, const char* comment)
     if (mCDE.mFileCommentLength > 0) {
         /* TODO: stop assuming null-terminated ASCII here? */
         mCDE.mFileComment = new uint8_t[mCDE.mFileCommentLength+1];
+        assert(comment != NULL);
         strcpy((char*) mCDE.mFileComment, comment);
     }