Travis Mac CI running out of memory on sysimg build

[Keno]

It looks like the OS X builder are running our of memory on travis.
Not sure if anything major changed recently, but let's try to find out.

[KristofferC]

Example log https://travis-ci.org/JuliaLang/julia/jobs/427715475

Stacktrace

error during bootstrap:
LoadError("sysimg.jl", 446, LoadError("version.jl", 50, ErrorException("PCRE JIT error: no more memory")))
rec_backtrace at /Users/travis/build/JuliaLang/julia/src/stackwalk.c:94
record_backtrace at /Users/travis/build/JuliaLang/julia/src/task.c:249 [inlined]
jl_throw at /Users/travis/build/JuliaLang/julia/src/task.c:580
error at ./error.jl:33
jit_compile at ./pcre.jl:110 [inlined]
compile at ./regex.jl:70

so doesn't seem to be the at the same place as there were problems before (LLVM native codegen).

version.jl:50 is

julia/base/version.jl

Line 50 in b4c370d

if !occursin(r"^(?:|[0-9a-z-]*[a-z-][0-9a-z-]*)$"i, ident) ||

[Keno]

The fact that PCRE always shows up in these is indeed a bit suspicious. We use system pcre on OS X, so perhaps that got updated without our knowledge?

[JeffBezanson]

Assuming fixed by #29162.