zipalign supports -p also when checking alignment.

This updates the usage banner of zipalign to state that the -p switch
is supported in check alignment mode.

Change-Id: I119026b0e09e5a2528646e88a9b58dbb79c0c17c
diff --git a/tools/zipalign/ZipAlign.cpp b/tools/zipalign/ZipAlign.cpp
index a2dfd02..aef91a5 100644
--- a/tools/zipalign/ZipAlign.cpp
+++ b/tools/zipalign/ZipAlign.cpp
@@ -33,12 +33,12 @@
     fprintf(stderr, "Copyright (C) 2009 The Android Open Source Project\n\n");
     fprintf(stderr,
         "Usage: zipalign [-f] [-p] [-v] [-z] <align> infile.zip outfile.zip\n"
-        "       zipalign -c [-v] <align> infile.zip\n\n" );
+        "       zipalign -c [-p] [-v] <align> infile.zip\n\n" );
     fprintf(stderr,
         "  <align>: alignment in bytes, e.g. '4' provides 32-bit alignment\n");
     fprintf(stderr, "  -c: check alignment only (does not modify file)\n");
     fprintf(stderr, "  -f: overwrite existing outfile.zip\n");
-    fprintf(stderr, "  -p: page align stored shared object files\n");
+    fprintf(stderr, "  -p: memory page alignment for stored shared object files\n");
     fprintf(stderr, "  -v: verbose output\n");
     fprintf(stderr, "  -z: recompress using Zopfli\n");
 }