internal/buildcfg: fix typo in DWARF 5 enabling code

Fix a typo in the code that decides which GOOS values will support use
of DWARF 5 ("darwin" was not spelled correctly).

Updates #26379.

Change-Id: I3a7906d708550fcedc3a8e89d0444bf12b9143f1
Reviewed-on: https://go-review.googlesource.com/c/go/+/656895
Auto-Submit: Ian Lance Taylor <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: David Chase <[email protected]>

Author: thanm

src/internal/buildcfg/exp.go

@@ -82,7 +82,7 @@ func ParseGOEXPERIMENT(goos, goarch, goexp string) (*ExperimentFlags, error) {
 	// XCOFF format (as far as can be determined) doesn't seem to
 	// support the necessary section subtypes for DWARF-specific
 	// things like .debug_addr (needed for DWARF 5).
-	dwarf5Supported := (goos != "dwarwin" && goos != "ios" && goos != "aix")
+	dwarf5Supported := (goos != "darwin" && goos != "ios" && goos != "aix")
 
 	baseline := goexperiment.Flags{
 		RegabiWrappers:  regabiSupported,