Update fuzzer infrastructure for developers a little (#27403)

* add a config that will build fuzzers

* bazel run --config=fuzzer_asan //path/to:fuzzer fuzzes!

BUILD

@@ -58,6 +58,12 @@ config_setting(
     values = {"apple_platform_type": "ios"},
 )
 
+# Fuzzers can be built as fuzzers or as tests
+config_setting(
+    name = "grpc_build_fuzzers",
+    values = {"define": "grpc_build_fuzzers=true"},
+)
+
 selects.config_setting_group(
     name = "grpc_no_xds",
     match_any = [

test/core/util/grpc_fuzzer.bzl

@@ -18,12 +18,18 @@ def grpc_fuzzer(name, corpus, srcs = [], deps = [], data = [], size = "large", *
     grpc_cc_test(
         name = name,
         srcs = srcs,
-        deps = deps + ["//test/core/util:fuzzer_corpus_test"],
+        deps = deps + select({
+            "//:grpc_build_fuzzers": [],
+            "//conditions:default": ["//test/core/util:fuzzer_corpus_test"],
+        }),
         data = data + native.glob([corpus + "/**"]),
         external_deps = [
             "gtest",
         ],
         size = size,
-        args = ["--directory=" + native.package_name() + "/" + corpus],
+        args = select({
+            "//:grpc_build_fuzzers": [native.package_name() + "/" + corpus],
+            "//conditions:default": ["--directory=" + native.package_name() + "/" + corpus],
+        }),
         **kwargs
     )

tools/bazel.rc

@@ -25,6 +25,20 @@ build:asan --linkopt=-fsanitize=address
 build:asan --action_env=ASAN_OPTIONS=detect_leaks=1:color=always
 build:asan --action_env=LSAN_OPTIONS=suppressions=test/core/util/lsan_suppressions.txt:report_objects=1
 
+build:fuzzer_asan --strip=never
+build:fuzzer_asan --define=grpc_build_fuzzers=true
+build:fuzzer_asan --copt=-fsanitize=fuzzer,address
+build:fuzzer_asan --copt=-fsanitize-coverage=edge
+build:fuzzer_asan --copt=-fsanitize-coverage=trace-cmp
+build:fuzzer_asan --copt=-O0
+build:fuzzer_asan --copt=-fno-omit-frame-pointer
+build:fuzzer_asan --copt=-DGPR_NO_DIRECT_SYSCALLS
+build:fuzzer_asan --copt=-DGRPC_ASAN
+build:fuzzer_asan --copt=-DADDRESS_SANITIZER  # used by absl
+build:fuzzer_asan --linkopt=-fsanitize=fuzzer,address
+build:fuzzer_asan --action_env=ASAN_OPTIONS=detect_leaks=1:color=always
+build:fuzzer_asan --action_env=LSAN_OPTIONS=suppressions=test/core/util/lsan_suppressions.txt:report_objects=1
+
 # We have a separate ASAN config for Mac OS to workaround a couple of bugs:
 # 1. https://github.com/bazelbuild/bazel/issues/6932
 #    _FORTIFY_SOURCE=1 is enabled by default on Mac OS, which breaks ASAN.