Zipalign: Avoid unnecessary padding

Problem: Aligned entry always get padded to the next aligned slot.
Solution: Fix alignment test.

Bug: 199932309
Test: align_test.cpp
Change-Id: I1e61c67dcf45454dd782d0fcc6903f7e71954083
diff --git a/tools/zipalign/ZipFile.cpp b/tools/zipalign/ZipFile.cpp
index 6037d59..f2f65a6 100644
--- a/tools/zipalign/ZipFile.cpp
+++ b/tools/zipalign/ZipFile.cpp
@@ -530,7 +530,7 @@
     // If the alignment is not what was requested, add some padding in the extra
     // so the payload ends up where is requested.
     uint64_t alignDiff = alignTo - (expectedPayloadOffset % alignTo);
-    if (alignDiff == 0)
+    if (alignDiff == alignTo)
         return OK;
 
     return pEntry->addPadding(alignDiff);