Reusing the previous build's mapping returns every pre-existing symbol to its
old name, which silently undoes the randomisation while every build-side check
still passes. Deleting the mapping file before each build worked but left the
guarantee resting on the caller.
Upstream assigns obfuscated names from a monotonic base-52 counter, so two
builds of the same source produce an identical mapping and a build with a
small source change keeps almost every previous name. An attacker who
reverses build N therefore carries that work forward to build N+1.
nameRandomSeed = 0 keeps the original counter, so this is opt-in and the
default behaviour is unchanged.
Gabriel Olivato
walon