[clang] [C] Add -Wjump-bypasses-init (PR #138009)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> this causes a `-Wmicrosoft-goto` warning on
> 
> ```
> $ cat /tmp/a.c
> void f() {
>         goto l;
>         int i = 0;
> l:
> }
> $ bin/clang-cl /c /tmp/a.c
> ...
> /tmp/a.c(2,2): warning: jump from this goto statement to its label is a Microsoft extension [-Wmicrosoft-goto]
>     2 |         goto l;
>       |         ^
> /tmp/a.c(3,6): note: jump bypasses variable initialization
>     3 |         int i = 0;
>       |             ^
> ```
> 
> where there was none previously. is this intended?

No, that was not intended; thank you to @zmodem for that fix

https://github.com/llvm/llvm-project/pull/138009