[LSan] Detect dynamic loader by its base address.

[LSan] Detect dynamic loader by its base address.

Summary:
Relanding D38600, which was reverted due to various PPC bot failures.

If it breaks something again, please provide some pointers to broken
bots, not just revert it, otherwise it's very hard to reason what's
wrong with this commit.

Whenever possible (Linux + glibc 2.16+), detect dynamic loader module by
its base address, not by the module name matching. The current name
matching approach fails on some configurations.

Reviewers: eugenis

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D39275

llvm-svn: 317512