Improve rule() api and add some builtin rules

[waruqi]

in version(2.2.1):

add_rules("mode.debug", "mode.release")

target("console_c")
    set_kind("binary")
    add_files("src/*.c") 

Before:

if is_mode("debug") then
    set_symbols("debug")
    set_optimize("none")
end

if is_mode("release") then
    set_symbols("hidden")
    set_optimize("fastest")
    set_strip("all")
end

target("console_c")
    set_kind("binary")
    add_files("src/*.c") 

[waruqi]

xmake will provide some builtin rules in xmake/rules, for example:

-- define rule: debug mode
rule("mode.debug")
    on_load(function (target)

        -- is debug mode now? xmake f -m debug
        if is_mode("debug") then
 
            -- enable the debug symbols
            target:set("symbols", "debug")

            -- disable optimization
            target:set("optimize", "none")
        end
    end)

[waruqi]

#149

[waruqi]

Some rule apis:

• add_deps
• set_extensions
• on_load
• on_build
• on_build_file
• on_build_files
• before_build
• before_build_file
• before_build_files
• after_build
• after_build_file
• after_build_files
• on_clean, on_install, on_uninstall, on_run, on_package
• before_xxx, after_xxx ...

All rules are superimposed on the specified target.

[waruqi]

We will provide some qt rules #160 to implement it, for example:

target("qt_test1")
    add_rules("qt.console")
    add_files("src/*.cpp")

target("qt_test2")
    add_rules("qt.application")
    add_files("src/*.cpp")

[waruqi]

Support multi-rules in same files.

rule("rule1")
    before_build_file(function (target, sourcefile)
    end)
rule("rule2")
    after_build_file(function (target, sourcefile)
    end)
target("console_c")
    set_kind("binary")
    add_files("src/*.c", {rules = {"rule1", "rule2"}}) 

[waruqi]

See Online docs about rules