[analyzer] Don't reinitialize static globals more than once along a path

[analyzer] Don't reinitialize static globals more than once along a path

This patch makes sure that we do not reinitialize static globals when
the function is called more than once along a path. The motivation is
code with initialization patterns that rely on 2 static variables, where
one of them has an initializer while the other does not. Currently, we
reset the static variables with initializers on every visit to the
function along a path.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174676 91177308-0d34-0410-b5e6-96231b3b80d8