soong_config: Allow extension of valid gralloc 1.0 buffer usage bits

* fw/native change I7f4174581e24e361577640b9263514a168ed482d
  implemented validation of the buffer description info prior to
  creating the descriptor. Some of our legacy devices need to
  whitelist additional usage bits to support various functionality.
* The TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS variable can contain
  a singular roll-up value (e.g., 0x02000000U), a left-shifted bit
  (e.g., (1 << 25)), a bitwise OR of these things, or essentially
  anything that the compiler can choke down.

Change-Id: I2127d33b03426b5e0f981aae837e07d82163fa17
diff --git a/build/soong/android/variable.go b/build/soong/android/variable.go
index c2bb782..5e992ca 100644
--- a/build/soong/android/variable.go
+++ b/build/soong/android/variable.go
@@ -1,5 +1,8 @@
 package android
 type Product_variables struct {
+	Additional_gralloc_10_usage_bits struct {
+		Cppflags []string
+	}
 	Has_legacy_camera_hal1 struct {
 		Cflags []string
 	}
@@ -25,6 +28,7 @@
 }
 
 type ProductVariables struct {
+	Additional_gralloc_10_usage_bits  *string `json:",omitempty"`
 	Has_legacy_camera_hal1  *bool `json:",omitempty"`
 	Needs_text_relocations  *bool `json:",omitempty"`
 	Specific_camera_parameter_library  *string `json:",omitempty"`
diff --git a/build/soong/soong_config.mk b/build/soong/soong_config.mk
index 577d29d..accd467 100644
--- a/build/soong/soong_config.mk
+++ b/build/soong/soong_config.mk
@@ -3,6 +3,7 @@
 _contents := $(_contents)    "Lineage":{$(newline)
 
 # See build/core/soong_config.mk for the add_json_* functions you can use here.
+$(call add_json_str_omitempty, Additional_gralloc_10_usage_bits, $(TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS))
 $(call add_json_bool, Has_legacy_camera_hal1, $(filter true,$(TARGET_HAS_LEGACY_CAMERA_HAL1)))
 $(call add_json_bool, Needs_text_relocations, $(filter true,$(TARGET_NEEDS_PLATFORM_TEXT_RELOCATIONS)))
 $(call add_json_str, Specific_camera_parameter_library, $(TARGET_SPECIFIC_CAMERA_PARAMETER_LIBRARY))