Disable bazel for riscv_64

This product is experimental and unsupported for Bazel at this time

Test: lunch aosp_riscv64-userdebug && m nothing
Test: lunch aosp_arm64-userdebug && m nothing
Change-Id: I761afb9524f1008f9d5472d2de19bb84342e9e29
diff --git a/android/config.go b/android/config.go
index 1deb7d4..52a8f13 100644
--- a/android/config.go
+++ b/android/config.go
@@ -536,7 +536,17 @@
 // Returns true if "Bazel builds" is enabled. In this mode, part of build
 // analysis is handled by Bazel.
 func (c *config) IsMixedBuildsEnabled() bool {
-	return c.BuildMode == BazelProdMode || c.BuildMode == BazelDevMode || c.BuildMode == BazelStagingMode
+	globalMixedBuildsSupport := c.Once(OnceKey{"globalMixedBuildsSupport"}, func() interface{} {
+		if c.productVariables.DeviceArch != nil && *c.productVariables.DeviceArch == "riscv64" {
+			fmt.Fprintln(os.Stderr, "unsupported device arch 'riscv64' for Bazel: falling back to non-mixed build")
+			return false
+		}
+		// TODO(b/253664931): Add other fallback criteria below.
+		return true
+	}).(bool)
+
+	bazelModeEnabled := c.BuildMode == BazelProdMode || c.BuildMode == BazelDevMode || c.BuildMode == BazelStagingMode
+	return globalMixedBuildsSupport && bazelModeEnabled
 }
 
 func (c *config) SetAllowMissingDependencies() {