rust: Add missing variation -D flags to bindgen.

rust_bindgen calls are missing a large set of -D cflags which control
how headers are interpretted for certain variations (such as
-D__ANDROID_VNDK__). This CL introduces the full set of these flags.

Bug: 205609024
Test: rust_bindgen vendor variant builds correctly.

Change-Id: Id781c1f88352e9c238c49619f0dce20f804cfc77
diff --git a/rust/bindgen.go b/rust/bindgen.go
index 845f258..32d02e4 100644
--- a/rust/bindgen.go
+++ b/rust/bindgen.go
@@ -15,6 +15,7 @@
 package rust
 
 import (
+	"fmt"
 	"strings"
 
 	"github.com/google/blueprint"
@@ -147,6 +148,31 @@
 	cflags = append(cflags, strings.ReplaceAll(ccToolchain.Cflags(), "${config.", "${cc_config."))
 	cflags = append(cflags, strings.ReplaceAll(ccToolchain.ToolchainCflags(), "${config.", "${cc_config."))
 
+	if ctx.RustModule().UseVndk() {
+		cflags = append(cflags, "-D__ANDROID_VNDK__")
+		if ctx.RustModule().InVendor() {
+			cflags = append(cflags, "-D__ANDROID_VENDOR__")
+		} else if ctx.RustModule().InProduct() {
+			cflags = append(cflags, "-D__ANDROID_PRODUCT__")
+		}
+	}
+
+	if ctx.RustModule().InRecovery() {
+		cflags = append(cflags, "-D__ANDROID_RECOVERY__")
+	}
+
+	if mctx, ok := ctx.(*moduleContext); ok && mctx.apexVariationName() != "" {
+		cflags = append(cflags, "-D__ANDROID_APEX__")
+		if ctx.Device() {
+			cflags = append(cflags, fmt.Sprintf("-D__ANDROID_APEX_MIN_SDK_VERSION__=%d",
+				ctx.RustModule().apexSdkVersion.FinalOrFutureInt()))
+		}
+	}
+
+	if ctx.Target().NativeBridge == android.NativeBridgeEnabled {
+		cflags = append(cflags, "-D__ANDROID_NATIVE_BRIDGE__")
+	}
+
 	// Dependency clang flags and include paths
 	cflags = append(cflags, deps.depClangFlags...)
 	for _, include := range deps.depIncludePaths {