Allow boards to turn overriding commands into an error

Many boards have warnings like this, saying that we defined a build
rule, but later something else came in and overrode it with something
else:

art/build/Android.gtest.mk:677: warning: overriding commands for target `test-art-target-gtest-cmdline_parser_test'
art/build/Android.gtest.mk:674: warning: ignoring old commands for target `test-art-target-gtest-cmdline_parser_test'

Beyond the obvious problem of replacing the rule with something else,
target-specific variables can be combined as well, leading to some very
strange problems.

Since so many boards still have problems like this, but we don't
currently have any global problems, add a flag so that we can mark
boards as not broken. This should prevent regressions while we clean up
the individual problems.

Once the non-broken devices number significantly more than the broken
devices, we'll switch this default. And once they're all cleaned up this
variable will become obsolete, and these warnings will always be errors.

Bug: 77611511
Test: lunch aosp_arm-eng; m nothing
Test: lunch aosp_marlin-eng; m nothing
Test: build_test on all downstream branches
Change-Id: I43b645658f468c23a5b9ebcfcd9d4516537db540

core/config.mk

@@ -189,6 +189,12 @@ else
 JAVA_TMPDIR_ARG :=
 endif
 
+# ###############################################################
+# Broken build defaults
+# ###############################################################
+# Assume that all boards have duplicate rules right now.
+BUILD_BROKEN_DUP_RULES := true
+
 # ###############################################################
 # Include sub-configuration files
 # ###############################################################

target/board/generic/BoardConfig.mk

@@ -69,4 +69,6 @@ BOARD_PROPERTY_OVERRIDES_SPLIT_ENABLED := true
 TARGET_NO_RECOVERY := true
 BOARD_BUILD_SYSTEM_ROOT_IMAGE := true
 
-BOARD_VNDK_VERSION := current
+BOARD_VNDK_VERSION := current
+
+BUILD_BROKEN_DUP_RULES := false

target/board/generic_arm64/BoardConfig.mk

@@ -101,3 +101,5 @@ TARGET_NO_RECOVERY := true
 BOARD_BUILD_SYSTEM_ROOT_IMAGE := true
 
 BOARD_VNDK_VERSION := current
+
+BUILD_BROKEN_DUP_RULES := false

target/board/generic_mips64/BoardConfig.mk

@@ -91,3 +91,5 @@ DEX_PREOPT_DEFAULT := nostripping
 # Enable A/B update
 TARGET_NO_RECOVERY := true
 BOARD_BUILD_SYSTEM_ROOT_IMAGE := true
+
+BUILD_BROKEN_DUP_RULES := false

target/board/generic_x86/BoardConfig.mk

@@ -63,6 +63,8 @@ BOARD_SEPOLICY_DIRS += \
 
 BOARD_VNDK_VERSION := current
 
+BUILD_BROKEN_DUP_RULES := false
+
 # Enable A/B update
 TARGET_NO_RECOVERY := true
 BOARD_BUILD_SYSTEM_ROOT_IMAGE := true

target/board/generic_x86_64/BoardConfig.mk

@@ -65,3 +65,5 @@ BOARD_VNDK_VERSION := current
 # Enable A/B update
 TARGET_NO_RECOVERY := true
 BOARD_BUILD_SYSTEM_ROOT_IMAGE := true
+
+BUILD_BROKEN_DUP_RULES := false

target/board/treble_common.mk

@@ -58,3 +58,5 @@ ifeq ($(BOARD_AVB_ENABLE),true)
 $(error BOARD_AVB_ENABLE cannot be set for Treble GSI)
 endif
 BOARD_BUILD_DISABLED_VBMETAIMAGE := true
+
+BUILD_BROKEN_DUP_RULES := false