Roll AFL 2.31b:2.38b and switch coverage to use trace-pc-guard.

third_party/afl/src/afl-gcc.c

Index: third_party/afl/src/afl-gcc.c
diff --git a/third_party/afl/src/afl-gcc.c b/third_party/afl/src/afl-gcc.c
index 1a588da978e5e5eca9ea801d463c587081c3135b..fa3dec1aaeb0d43ad70793baf2f29249b160ea1c 100644
--- a/third_party/afl/src/afl-gcc.c
+++ b/third_party/afl/src/afl-gcc.c
@@ -229,18 +229,27 @@ static void edit_params(u32 argc, char** argv) {
 
   } else if (getenv("AFL_USE_ASAN")) {
 
-    cc_params[cc_par_cnt++] = "-fsanitize=address";
-
     if (getenv("AFL_USE_MSAN"))
       FATAL("ASAN and MSAN are mutually exclusive");
 
-  } else if (getenv("AFL_USE_MSAN")) {
+    if (getenv("AFL_HARDEN"))
+      FATAL("ASAN and AFL_HARDEN are mutually exclusive");
 
-    cc_params[cc_par_cnt++] = "-fsanitize=memory";
+    cc_params[cc_par_cnt++] = "-U_FORTIFY_SOURCE";
+    cc_params[cc_par_cnt++] = "-fsanitize=address";
+
+  } else if (getenv("AFL_USE_MSAN")) {
 
     if (getenv("AFL_USE_ASAN"))
       FATAL("ASAN and MSAN are mutually exclusive");
 
+    if (getenv("AFL_HARDEN"))
+      FATAL("MSAN and AFL_HARDEN are mutually exclusive");
+
+    cc_params[cc_par_cnt++] = "-U_FORTIFY_SOURCE";
+    cc_params[cc_par_cnt++] = "-fsanitize=memory";
+
+
   }
 
   if (!getenv("AFL_DONT_OPTIMIZE")) {
@@ -314,7 +323,6 @@ int main(int argc, char** argv) {
 
   }
 
-
   find_as(argv[0]);
 
   edit_params(argc, argv);