Jump table labels change from ".Lxxxxx_yy" to "$Jxxxxx_yy".

Pooled float labels change from ".L$float$xxxxyyyy" to "$Fxxxxyyyy".

Pooled double labels change from ".L$double$xxxxxxxxyyyyyyyy" to "$Dxxxxxxxxyyyyyyyy".

All these should in theory not conflict with C/C++ user symbols.

Float labels now likely fit into short strings and don't require extra memory allocation.

Double labels may exceed the limit - encoding in base64 instead of hex would fix that.  Or, directly use the binary bytes as the string value.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1868113002 .