[analyzer; alternate edges] don't add an edge incoming from the start of a function
for a nested call.  This matches what we do with the first stack frame.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182078 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer; alternate edges] treat 'if' statements the same way we do as 'for' or 'while'.

This means adding an extra edge from the 'if' to the condition,
which aesthetically looks more pleasing.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182079 91177308-0d34-0410-b5e6-96231b3b80d8