Accept CLANG_COVERAGE_CONTINUOUS_MODE build variable

Bug: http://b/194128476

Coverage instrumentation will support continuous mode when this flag is
set.

Test: CLANG_COVERAGE_CONTINUOUS_MODE m and verify continuous mode works.
Change-Id: I187574c600ba10145dfb2c6c23551d235c33103a
diff --git a/core/soong_config.mk b/core/soong_config.mk
index c24df60..fd957c3 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -119,6 +119,7 @@
 
 $(call add_json_bool, GcovCoverage,                      $(filter true,$(NATIVE_COVERAGE)))
 $(call add_json_bool, ClangCoverage,                     $(filter true,$(CLANG_COVERAGE)))
+$(call add_json_bool, ClangCoverageContinuousMode,       $(filter true,$(CLANG_COVERAGE_CONTINUOUS_MODE)))
 $(call add_json_list, NativeCoveragePaths,               $(NATIVE_COVERAGE_PATHS))
 $(call add_json_list, NativeCoverageExcludePaths,        $(NATIVE_COVERAGE_EXCLUDE_PATHS))