Add new Release_aidl_use_unfrozen soong variable

this comes from a trunk stable build flag `RELEASE_AIDL_USE_UNFROZEN`
and is used by the AIDL compiler when creating build rules for the
generated AIDL libraries.

Test: m
Bug: 290265210
Change-Id: I94445c870ac908474e62db0b3172b64d53680852

android/variable.go

@@ -180,6 +180,13 @@ type variableProperties struct {
 			Srcs         []string `android:"arch_variant"`
 			Exclude_srcs []string `android:"arch_variant"`
 		} `android:"arch_variant"`
+
+		// release_aidl_use_unfrozen is "true" when a device can
+		// use the unfrozen versions of AIDL interfaces.
+		Release_aidl_use_unfrozen struct {
+			Cflags []string
+			Cmd    *string
+		}
 	} `android:"arch_variant"`
 }
 
@@ -457,6 +464,8 @@ type ProductVariables struct {
 
 	SelinuxIgnoreNeverallows bool `json:",omitempty"`
 
+	Release_aidl_use_unfrozen *bool `json:",omitempty"`
+
 	SepolicyFreezeTestExtraDirs         []string `json:",omitempty"`
 	SepolicyFreezeTestExtraPrebuiltDirs []string `json:",omitempty"`