Drop minix-malloc & friends

Known limitations:
 - comment for now testisofs, as iso9660fs is known to be broken.

Benefits:
 - near 3x speed improvement on C++ code compilation, bringing down
   make build to from 44min down to 21min.

 - Allows for X applications to work properly, which should be available
   in near-term future through pkgsrc for 3.3.0.

Change-Id: I8f4179a7ea925ed381642add32cfd8c5822217e4