[analyzer] Enable c++-allocator-inlining by default.

This allows the analyzer to analyze ("inline") custom operator new() calls and,
even more importantly, inline constructors of objects that were allocated
by any operator new() - not necessarily a custom one.

All changes in the tests in the current commit are intended improvements,
even if they didn't carry any explicit FIXME flag.

It is possible to restore the old behavior via

  -analyzer-config c++-allocator-inlining=false

(this flag is supported by scan-build as well, and it can be into a clang
--analyze invocation via -Xclang .. -Xclang ..). There is no intention to
remove the old behavior for now.

Differential Revision: https://reviews.llvm.org/D42219
rdar://problem/12180598

llvm-svn: 323373