odoc html-targets segfaults on odoc pages

[dbuenzli]

Steps to reproduce:

> mkdir /tmp/doc 
> odoc --version 
1.3.0
> odoc compile --pkg odoc -o /tmp/page-index.odoc $(opam var odoc:doc)/odoc-pages/index.mld 
> odoc html-targets --output-dir /tmp/doc /tmp/page-index.odoc 
Segmentation fault: 11

I suspect some kind of infinite loop this may help: (see below)

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0xb09)
    frame #0: 0x00000001000cf4ab odoc`camlModel__Maps__list_map_1542 + 27
odoc`camlModel__Maps__list_map_1542:
->  0x1000cf4ab <+27>: movq   0x8(%rbx), %rax
    0x1000cf4af <+31>: movq   %rax, 0x18(%rsp)
    0x1000cf4b4 <+36>: movq   (%rbx), %rax
    0x1000cf4b7 <+39>: movq   %rax, (%rsp)
Target 0: (odoc) stopped.

[dbuenzli]

In fact it segfaults around here I suspect the odoc file should not be loaded as a Compilation_unit or something like this.