Use tarval_cmp instead of pointer comparison in the duplicate case check.
fix typo
add -Wpointer-sign for gcc compatibility

Casting int* to unsigned* is allowed when this warning is disabled
even though the C standard says they are incompatible.
more exact definition of FLT_EVAL_METHOD
ignore more gcc switches
pass -nostdlib to the linker
casts to non integers are not integer constants
do not explicitely compare with type_void_ptr

We have to check for an unqualified pointer to a void_type after
skip_typeref, otherwise we incorrectly miss typeof expressions.
Use MIN().