Installation fails on OS X, due to bogus missing dependency

[yminsky]

I'm pretty sure I've seen something like this before, but installing re2 fails on the inability to find "cc -O2 -pipe", which seems weird to me. Unsurprisingly, "opam depext" doesn't find produce any useful results.

$ opam install re2
The following actions will be performed:
  ∗  install re2 v0.10.0

=-=- Gathering sources =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
[re2] Archive in cache

=-=- Processing actions -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
[ERROR] The compilation of re2 failed at "jbuilder build -p re2 -j 6".

#=== ERROR while installing re2.v0.10.0 =======================================#
# opam-version 1.2.2
# os           darwin
# command      jbuilder build -p re2 -j 6
# path         /Users/yminsky/.opam/4.06.0/build/re2.v0.10.0
# compiler     4.06.0
# exit-code    1
# env-file     /Users/yminsky/.opam/4.06.0/build/re2.v0.10.0/re2-5304-1872ec.env
# stdout-file  /Users/yminsky/.opam/4.06.0/build/re2.v0.10.0/re2-5304-1872ec.out
# stderr-file  /Users/yminsky/.opam/4.06.0/build/re2.v0.10.0/re2-5304-1872ec.err
### stderr ###
# Error: Program cc -O2 -pipe not found in PATH (context: default)



=-=- Error report -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
The following actions failed
  ∗  install re2 v0.10.0
No changes have been performed

=-=- re2.v0.10.0 troobleshooting =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=  🐫
=> This package relies on external (system) dependencies that may be missing. `opam depext re2.v0.10.0' may help you find the
   correct installation for your system.

[yminsky]

This is a re-mergence of #22