Switch sanitizer_procmaps_bsd to internal_sysctl

Summary:
Stop using directly sysctl(3) routines in sanitizer_procmaps_bsd
and replace it with internal_sysctl().

This will allow to install interceptors for sysctl(3).

Reviewers: joerg, vitalybuka

Reviewed By: vitalybuka

Subscribers: kubamracek, llvm-commits, #sanitizers

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D52646

llvm-svn: 343370