[kernel] add option -json-compilation-database

.gitignore

Makefile

configure.in

doc/userman/user-changes.tex

doc/userman/user-sources.tex

headers/header_spec.txt

man/frama-c.1

share/Makefile.config.in

src/kernel_services/ast_queries/file.ml

...rnel_services/ast_queries/json_compilation_database.ko.ml

...kernel_services/ast_queries/json_compilation_database.mli

...rnel_services/ast_queries/json_compilation_database.ok.ml

src/kernel_services/plugin_entry_points/kernel.ml

src/kernel_services/plugin_entry_points/kernel.mli