Merge pull request #1537 from AFLplusplus/dev

afl-persistent-config

afl-system-config

custom_mutators/gramatron/build_gramatron_mutator.sh

custom_mutators/gramatron/json-c

custom_mutators/grammar_mutator/build_grammar_mutator.sh

docs/Changelog.md

docs/custom_mutators.md

include/config.h

instrumentation/afl-compiler-rt.o.c

instrumentation/afl-gcc-cmplog-pass.so.cc

instrumentation/afl-gcc-cmptrs-pass.so.cc

instrumentation/afl-gcc-common.h

instrumentation/afl-gcc-pass.so.cc