Add Fibre local storage (Fls*) functions for armcc

[mkst]

I dunno if there is a better way than copy/paste to support these?

Closes #50:

$ ~/github/wibo/build/wibo armcc.exe
Product: unknown
Component: unknown
Tool: armcc [5040081]

Usage:         armcc [options] file1 file2 ... filen
Main options:
        
--arm          Generate ARM code
--thumb        Generate Thumb code
--c90          Switch to C mode (default for .c files)
--cpp          Switch to C++ mode (default for .cpp files)
-O0            Minimum optimization
-O1            Restricted optimization for debugging
-O2            High optimization
-O3            Maximum optimization
-Ospace        Optimize for codesize
-Otime         Optimize for maximum performance
--cpu <cpu>    Select CPU to generate code for
--cpu list     Output a list of all the selectable CPUs
--device <dev> Set the target device type
--device list  Output a list of all the selectable devices
-o <file>      Name the final output file of the compilation
-c             Compile only, do not link
--asm          Output assembly code as well as object code
-S             Output assembly code instead of object code
--interleave   Interleave source with disassembly (use with --asm or -S)
-E             Preprocess the C source code only
-D<symbol>     Define <symbol> on entry to the compiler
-g             Generate tables for high-level debugging
-I<directory>  Include <directory> on the #include search path

Note: just tried to use the Tls* functions, but armcc uses both FLS and TLS, so that's a no-go!