Add module dir to includes for cc_preprocess_no_configuration

This is needed to create the same behavior as other cc modules.

Bug: 372091092
Test: go test
Change-Id: I2c15dbc2c6a2b2ba693ef0f2a732525dd2f72d0f
diff --git a/cc/cc_preprocess_no_configuration.go b/cc/cc_preprocess_no_configuration.go
index 3d1d0a5..3d4b077 100644
--- a/cc/cc_preprocess_no_configuration.go
+++ b/cc/cc_preprocess_no_configuration.go
@@ -16,6 +16,7 @@
 
 import (
 	"android/soong/android"
+	"slices"
 	"strings"
 )
 
@@ -78,6 +79,12 @@
 		return
 	}
 
+	cflags := slices.Clone(m.properties.Cflags)
+
+	// Match behavior of other cc modules:
+	// https://cs.android.com/android/platform/superproject/main/+/main:build/soong/cc/compiler.go;l=422;drc=7297f05ee8cda422ccb32c4af4d9d715d6bac10e
+	cflags = append(cflags, "-I"+ctx.ModuleDir())
+
 	var ccCmd string
 	switch src.Ext() {
 	case ".c":
@@ -99,7 +106,7 @@
 		Output:      outFile,
 		Input:       src,
 		Args: map[string]string{
-			"cFlags": strings.Join(m.properties.Cflags, " "),
+			"cFlags": strings.Join(cflags, " "),
 			"ccCmd":  ccCmd,
 		},
 	})