* translate-c: Correctly translate enum init values
* translate-c: Test enum initialization
* translate-c: Flip to positive using APSInt builtins
* src/translate_c.cpp: correctly bridge llvm::APSInt with Zig BigInt;
ACHTUNG: llvm::APSInt stores an int's sign inside of its getRawData; Internally to Zig we store an integer's sign outside of getRawData! (~aps_int) calls .flip() internally on the raw data to match Zig.
* test/translate_c.zig: enum: add wider range of values (u64) to try;
closes#1360
b8ce8f219c