Modernize our libfuzzer usage to close #40407

Additionally, remove lingering references to hsv2 fuzzers from the
fuzzing_include_am.py script.

Makefile.am

@@ -253,7 +253,7 @@ endif
 TEST_NETWORK_SHOW_WARNINGS_FOR_LAST_RUN_FLAGS=--quiet --only-warnings
 
 if LIBFUZZER_ENABLED
-TEST_CFLAGS += -fsanitize-coverage=trace-pc-guard,trace-cmp,trace-div
+TEST_CFLAGS += -fsanitize=fuzzer-no-link
 # not "edge"
 endif
 

changes/bug40407

@@ -0,0 +1,5 @@
+  o Minor features (fuzzing):
+    - When building with --enable-libfuzzer, use a set of compiler flags
+      that works with more recent versions of the library.  Previously
+      we were using a set of flags from 2017.
+      Closes ticket 40407.

scripts/codegen/fuzzing_include_am.py

@@ -11,11 +11,9 @@ FUZZERS = """
 	diff
 	diff-apply
 	extrainfo
-	hsdescv2
 	hsdescv3
 	http
 	http-connect
-	iptsv2
 	microdesc
 	socks
 	strops
@@ -47,11 +45,10 @@ oss-fuzz-prereqs: \
 noinst_HEADERS += \
 	src/test/fuzz/fuzzing.h
 
-LIBFUZZER = -lFuzzer
 LIBFUZZER_CPPFLAGS = $(FUZZING_CPPFLAGS) -DLLVM_FUZZ
 LIBFUZZER_CFLAGS = $(FUZZING_CFLAGS)
-LIBFUZZER_LDFLAG = $(FUZZING_LDFLAG)
-LIBFUZZER_LIBS = $(FUZZING_LIBS) $(LIBFUZZER) -lstdc++
+LIBFUZZER_LDFLAG = $(FUZZING_LDFLAG) -fsanitize=fuzzer
+LIBFUZZER_LIBS = $(FUZZING_LIBS) -lstdc++
 
 LIBOSS_FUZZ_CPPFLAGS = $(FUZZING_CPPFLAGS) -DLLVM_FUZZ
 LIBOSS_FUZZ_CFLAGS = $(FUZZING_CFLAGS)

src/test/fuzz/include.am

@@ -23,11 +23,10 @@ oss-fuzz-prereqs: \
 noinst_HEADERS += \
 	src/test/fuzz/fuzzing.h
 
-LIBFUZZER = -lFuzzer
 LIBFUZZER_CPPFLAGS = $(FUZZING_CPPFLAGS) -DLLVM_FUZZ
 LIBFUZZER_CFLAGS = $(FUZZING_CFLAGS)
-LIBFUZZER_LDFLAG = $(FUZZING_LDFLAG)
-LIBFUZZER_LIBS = $(FUZZING_LIBS) $(LIBFUZZER) -lstdc++
+LIBFUZZER_LDFLAG = $(FUZZING_LDFLAG) -fsanitize=fuzzer
+LIBFUZZER_LIBS = $(FUZZING_LIBS) -lstdc++
 
 LIBOSS_FUZZ_CPPFLAGS = $(FUZZING_CPPFLAGS) -DLLVM_FUZZ
 LIBOSS_FUZZ_CFLAGS = $(FUZZING_CFLAGS)