SRC_HC_OPTS in perf build

[Edward Z. Yang]

Sounds like an oversight to me!  Submit a fix?

Excerpts from Jeremy's message of 2015-05-25 06:44:10 -0700:
> build.mk.sample contains the lines:
> 
> # perf matches the default settings, repeated here for comparison:
> SRC_HC_OPTS     = -O -H64m
> 
> However, in config.mk.in this is:
> 
> SRC_HC_OPTS += -H32m -O
> 
> What actually is the default for SRC_HC_OPTS? Why does config.mk.in seem to
> set it to -H32m, then every profile in build.mk.sample sets -H64m?
>