vendor: update buildkit to master@8b7bcb900d3c

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/golang.org/x/sys/execabs/execabs.go

@@ -63,7 +63,7 @@ func LookPath(file string) (string, error) {
 }
 
 func fixCmd(name string, cmd *exec.Cmd) {
-	if filepath.Base(name) == name && !filepath.IsAbs(cmd.Path) {
+	if filepath.Base(name) == name && !filepath.IsAbs(cmd.Path) && !isGo119ErrFieldSet(cmd) {
 		// exec.Command was called with a bare binary name and
 		// exec.LookPath returned a path which is not absolute.
 		// Set cmd.lookPathErr and clear cmd.Path so that it

vendor/golang.org/x/sys/execabs/execabs_go118.go

@@ -7,6 +7,12 @@
 
 package execabs
 
+import "os/exec"
+
 func isGo119ErrDot(err error) bool {
 	return false
 }
+
+func isGo119ErrFieldSet(cmd *exec.Cmd) bool {
+	return false
+}

vendor/golang.org/x/sys/execabs/execabs_go119.go

@@ -15,3 +15,7 @@ import (
 func isGo119ErrDot(err error) bool {
 	return errors.Is(err, exec.ErrDot)
 }
+
+func isGo119ErrFieldSet(cmd *exec.Cmd) bool {
+	return cmd.Err != nil
+}