diagnose_apk_bloat.py: fix error messages and simplify rev order.

tools/binary_size/README.md

 # Tools for analyzing Chrome's binary size
 
 # Super Size
 
 Collect, archive, and analyze Chrome's binary size.
 
 ## "archive"
 
 Collect size information and dump it into a `.size` file. Mainly consists of
 symbol information parsed from a linker .map file.
 
 ### Example Usage:
 
+Note: Supersize on Linux has known deficiencies (crbug/717550).
+
     # Android:
     # Googlers:
     gn gen out/Release --args='is_official_build=true symbol_level=1 is_chrome_branded=true target_os="android"'
     # Non-Googlers:
     gn gen out/Release --args='is_official_build=true symbol_level=1 exclude_unwind_tables=true ffmpeg_branding="Chrome" proprietary_codecs=true target_os="android"'
     ninja -C out/Release -j 1000 libchrome.so
     tools/binary_size/supersize archive chrome.size --elf-file out/Release/lib.unstripped/libchrome.so -v
 
     # Linux:
     LLVM_DOWNLOAD_GOLD_PLUGIN=1 gclient runhooks  # One-time download.
@@ skipping 79 matching lines @@
   * Break down by other groupings (e.g. create from nested `SymbolGroups`)
 
 1. Integrate with `resource_sizes.py` so that it tracks size of major
    components separately: chrome vs blink vs skia vs v8.
 1. Speed up some steps (like normalizing names) via multiprocessing.
 1. Add dependency graph info, perhaps just on a per-file basis.
 
 # Roadmap for diagnose_apk_bloat.py:
 1. More `diagnose_apk_bloat.py` features:
 
-  * Add more diff types (pak files, Java symbols, native symbols).
-  * Support local builds for revs before supersize existed.
+  * Add more diff types (pak files, Java symbols).