Move dbghelp64.rs to win64.rs

Windows 64-bit doesn't use dbghelp for tracing, so the name was confusing.

Author: ChrisDenton

src/backtrace/mod.rs

@@ -189,15 +189,15 @@ cfg_if::cfg_if! {
     } else if #[cfg(all(windows, not(target_vendor = "uwp")))] {
         cfg_if::cfg_if! {
             if #[cfg(any(target_arch = "x86_64", target_arch = "aarch64", target_arch = "arm64ec"))] {
-                mod dbghelp64;
-                use dbghelp64 as dbghelp;
+                mod win64;
+                use self::win64::trace as trace_imp;
+                pub(crate) use self::win64::Frame as FrameImp;
             } else if #[cfg(any(target_arch = "x86", target_arch = "arm"))] {
                 mod dbghelp32;
-                use dbghelp32 as dbghelp;
+                use self::dbghelp32::trace as trace_imp;
+                pub(crate) use self::dbghelp32::Frame as FrameImp;
             }
         }
-        use self::dbghelp::trace as trace_imp;
-        pub(crate) use self::dbghelp::Frame as FrameImp;
     } else {
         mod noop;
         use self::noop::trace as trace_imp;

src/backtrace/dbghelp64.rs renamed to src/backtrace/win64.rs

@@ -77,11 +77,6 @@ impl MyContext {
     }
 }
 
-#[cfg(any(
-    target_arch = "x86_64",
-    target_arch = "aarch64",
-    target_arch = "arm64ec"
-))]
 #[inline(always)]
 pub unsafe fn trace(cb: &mut dyn FnMut(&super::Frame) -> bool) {
     use core::ptr;