[Clang] [Cygwin] wint_t is unsigned int (#143117)

On Cygwin environment, wint_t is unsigned int as shown here:
```
$ echo | gcc -m32 -xc - -E -dM | grep WINT_T
145:#define __SIZEOF_WINT_T__ 4
315:#define __WINT_TYPE__ unsigned int
```

```
$ echo | gcc -xc - -E -dM | grep WINT_T
147:#define __SIZEOF_WINT_T__ 4
317:#define __WINT_TYPE__ unsigned int
```

```
$ LANG=C gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/15/lto-wrapper.exe
Target: x86_64-pc-cygwin
(snip)
```

Author: kikairoya

clang/lib/Basic/Targets/X86.h

@@ -647,6 +647,7 @@ class LLVM_LIBRARY_VISIBILITY CygwinX86_32TargetInfo : public X86_32TargetInfo {
   CygwinX86_32TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : X86_32TargetInfo(Triple, Opts) {
     this->WCharType = TargetInfo::UnsignedShort;
+    this->WIntType = TargetInfo::UnsignedInt;
     DoubleAlign = LongLongAlign = 64;
     resetDataLayout("e-m:x-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-"
                     "i128:128-f80:32-n8:16:32-a:0:32-S32",
@@ -982,6 +983,7 @@ class LLVM_LIBRARY_VISIBILITY CygwinX86_64TargetInfo : public X86_64TargetInfo {
   CygwinX86_64TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : X86_64TargetInfo(Triple, Opts) {
     this->WCharType = TargetInfo::UnsignedShort;
+    this->WIntType = TargetInfo::UnsignedInt;
   }
 
   void getTargetDefines(const LangOptions &Opts,