Add BUILD_BROKEN_PREBUILT_ELF_FILES to dumpvars.go

This commit adds BUILD_BROKEN_PREBUILT_ELF_FILES to
`ui/build/dumpvars.go` so that its value can be printed to
`out/soong.log`.

Bug: 141176116
Test: lunch aosp_crosshatch-userdebug && make && \
      grep BUILD_BROKEN_PREBUILT_ELF_FILES out/soong.log

Change-Id: I99600a5b540be2bb93647ee8175b9f9afd1a6eb3
diff --git a/ui/build/dumpvars.go b/ui/build/dumpvars.go
index 6b9eac1..82b2750 100644
--- a/ui/build/dumpvars.go
+++ b/ui/build/dumpvars.go
@@ -208,6 +208,7 @@
 
 		"DEFAULT_WARNING_BUILD_MODULE_TYPES",
 		"DEFAULT_ERROR_BUILD_MODULE_TYPES",
+		"BUILD_BROKEN_PREBUILT_ELF_FILES",
 		"BUILD_BROKEN_USES_BUILD_AUX_EXECUTABLE",
 		"BUILD_BROKEN_USES_BUILD_AUX_STATIC_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_COPY_HEADERS",