[dsymutil] Enable -minimize feature.

Passing -minimize to dsymutil prevents the emission of .debug_inlines,
.debug_pubnames, and .debug_pubtypes in favor of the Apple accelerator
tables.

The actual check in the DWARF linker was added in r323655. This patch
simply enables it.

Differential revision: https://reviews.llvm.org/D42688

llvm-svn: 323812