Move cheap checks earlier to avoid more expensive ones
Fixed crash on garbage code introduced by recent commit.
Refactorization in checkmemoryleak.cpp:
- Use Library to detect noreturn/notnoreturn functions
- Removed realloc from std.cfg as long as there is no proper way to configure such functions
Attempt to fix crashs when self-checking cppcheck introduced by previous commit
Merge pull request #412 from Dmitry-Me/moveChecksEarlier

Move cheap checks earlier to avoid more expensive ones
Disabled several checks and simplifications for C code, if they are C++-only. Do not match arguments for C code, since there can't be overloads.
 #5805 'Passing value -1.0 to sqrt() leads to undefined result' is incorrect. Degrade wrongmathcall from error to warning, since it deals with implementation-defined behaviour
#6116 False positive uninitvar - first argument to wcstombs(). Correct stf.cfg
Handle ternary operator in redundantAssignment check (#5964)
Attempt to fix crashs on clang test suite.