Makefile: flags should not need `-`, same as std libs

[0xc0170]

tool_specific:
    gcc_arm:
        misc:
            c_flags:
                - -mfpu=fpv4-sp-d16
                - -mfloat-abi=softfp
                - -g 
                - -ggdb
                - -Os 
                - -Wall 
                - -fno-strict-aliasing
                - -ffunction-sections 
                - -fdata-sections 
                - -fno-exceptions 
                - -fno-delete-null-pointer-checks
                - -fmessage-length=0 
                - -fno-builtin 
                - -mthumb
                - -mcpu=cortex-m4
                - -MMD
                - -MP

vs

            standard_libraries:
                - m
                - gcc
                - c
                - nosys

this should be without -, as we parse them and add -

[flit]

But what about options that begin with --? Or toolchains that have options that don't begin with a dash, both those that start with / and no prefix.