[analyzer] Set the default IPA mode to 'basic-inlining', which excludes C++.

Under -analyzer-ipa=basic-inlining, only C functions, blocks, and C++ static
member functions are inlined -- essentially, the calls that behave like simple
C function calls. This is essentially the behavior in Xcode 4.4.

C++ support still has some rough edges, and we don't want users to be worried
about them if they download and run their own checker. (In particular, the
massive number of false positives for analyzing LLVM comes from inlining
defensively-written code in contexts where more aggressive assumptions are
implicitly made. This problem is not unique to C++, but it is exacerbated by
the higher proportion of code that lives in header files in C++.)

The eventual goal is to be comfortable enough with C++ support (and simple
Objective-C support) to advance to -analyzer-ipa=inlining as the default
behavior. See the IPA design notes for more details.

llvm-svn: 162318