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

third_party/afl/src/Makefile

 #
 # american fuzzy lop - makefile
 # -----------------------------
 #
 # Written and maintained by Michal Zalewski <lcamtuf@google.com>
 # 
 # Copyright 2013, 2014, 2015, 2016 Google Inc. All rights reserved.
 # 
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ skipping 105 matching lines @@
         $(MAKE) -C llvm_mode clean
         $(MAKE) -C libdislocator clean
         $(MAKE) -C libtokencap clean
 
 install: all
         mkdir -p -m 755 $${DESTDIR}$(BIN_PATH) $${DESTDIR}$(HELPER_PATH) $${DESTDIR}$(DOC_PATH) $${DESTDIR}$(MISC_PATH)
         rm -f $${DESTDIR}$(BIN_PATH)/afl-plot.sh
         install -m 755 $(PROGS) $(SH_PROGS) $${DESTDIR}$(BIN_PATH)
         rm -f $${DESTDIR}$(BIN_PATH)/afl-as
         if [ -f afl-qemu-trace ]; then install -m 755 afl-qemu-trace $${DESTDIR}$(BIN_PATH); fi
+ifndef AFL_TRACE_PC
         if [ -f afl-clang-fast -a -f afl-llvm-pass.so -a -f afl-llvm-rt.o ]; then set -e; install -m 755 afl-clang-fast $${DESTDIR}$(BIN_PATH); ln -sf afl-clang-fast $${DESTDIR}$(BIN_PATH)/afl-clang-fast++; install -m 755 afl-llvm-pass.so afl-llvm-rt.o $${DESTDIR}$(HELPER_PATH); fi
+else
+        if [ -f afl-clang-fast -a -f afl-llvm-rt.o ]; then set -e; install -m 755 afl-clang-fast $${DESTDIR}$(BIN_PATH); ln -sf afl-clang-fast $${DESTDIR}$(BIN_PATH)/afl-clang-fast++; install -m 755 afl-llvm-rt.o $${DESTDIR}$(HELPER_PATH); fi
+endif
         if [ -f afl-llvm-rt-32.o ]; then set -e; install -m 755 afl-llvm-rt-32.o $${DESTDIR}$(HELPER_PATH); fi
         if [ -f afl-llvm-rt-64.o ]; then set -e; install -m 755 afl-llvm-rt-64.o $${DESTDIR}$(HELPER_PATH); fi
         set -e; for i in afl-g++ afl-clang afl-clang++; do ln -sf afl-gcc $${DESTDIR}$(BIN_PATH)/$$i; done
         install -m 755 afl-as $${DESTDIR}$(HELPER_PATH)
         ln -sf afl-as $${DESTDIR}$(HELPER_PATH)/as
         install -m 644 docs/README docs/ChangeLog docs/*.txt $${DESTDIR}$(DOC_PATH)
         cp -r testcases/ $${DESTDIR}$(MISC_PATH)
         cp -r dictionaries/ $${DESTDIR}$(MISC_PATH)
 
 publish: clean
         test "`basename $$PWD`" = "afl" || exit 1
         test -f ~/www/afl/releases/$(PROGNAME)-$(VERSION).tgz; if [ "$$?" = "0" ]; then echo; echo "Change program version in config.h, mmkay?"; echo; exit 1; fi
         cd ..; rm -rf $(PROGNAME)-$(VERSION); cp -pr $(PROGNAME) $(PROGNAME)-$(VERSION); \
           tar -cvz -f ~/www/afl/releases/$(PROGNAME)-$(VERSION).tgz $(PROGNAME)-$(VERSION)
         chmod 644 ~/www/afl/releases/$(PROGNAME)-$(VERSION).tgz
         ( cd ~/www/afl/releases/; ln -s -f $(PROGNAME)-$(VERSION).tgz $(PROGNAME)-latest.tgz )
         cat docs/README >~/www/afl/README.txt
         cat docs/status_screen.txt >~/www/afl/status_screen.txt
         cat docs/historical_notes.txt >~/www/afl/historical_notes.txt
         cat docs/technical_details.txt >~/www/afl/technical_details.txt
         cat docs/ChangeLog >~/www/afl/ChangeLog.txt
         cat docs/QuickStartGuide.txt >~/www/afl/QuickStartGuide.txt
         echo -n "$(VERSION)" >~/www/afl/version.txt