add separate cxx options for gcc (#80) ...

* add separate cxx options for gcc

* remove warning write-strings

Don't use whole-archive linking (#71) ...

* First attempt at converting to OBJECT libraries.  Not working due to more object library limitations

* Only compile the main libraries as OBJECT, because that's all that CMake can be made to do right now.

* Fix availability of target-specific flags

* Missed some usages

* Fix some STM32 ethernet stuff that was not linking correctly

* More fixes for STM32 ethernet and weak symbols

* Fix prebuilt object file linking for MUSCA_S1

* Fix STM32 eth init license headers

Switch to cortex-debug plugin for VS Code to improve debugging experience

Add core flags dependency back to the target flags, making sure that the core flags headers actually work

Only support GCC ARM compiler, but reap the benefits of static libraries instead of objects

CMake: Do not set `CMAKE_AR` ...

The variable for archiver is automatically set by CMake. There is
no need to explicitly set it, unless a project really needs to
override the default archiver.

Configure memory map per target to allow multiple add_executable

CMake: Refactor mapfile generation ...

The refactoring was necessary to remove a function call
(mbed_configure_app_target()) from application's CMakeLists.txt.

Fix some formatting issues.

Rebase linker script change properly, re-add external toolchain file support

Also update ARM.cmake

Change toolchain file to load core and toolchain options *before* compilers are loaded.

CMake ARM: move map to unify with Gcc Arm

CMake: GCC ARM linker script fix ...

Fixes https://github.com/ARMmbed/mbed-os/issues/13983
Move linker script to the function mbed_set_mbed_target_linker_script.

I also moved memmap as it is needed for an app. The location might not be the best fit,
we will address this in separate pull request.

Merge pull request #13930 from LDong-Arm/arm_compiler_macros ...

CMake: pass macros to ARM toolchain linker

CMake: make linker option generator function toolchain-agnostic

CMake: Clean remnant of experiment with ARM toolchain ...

The removed code was testing that compiler flags could be added
to the assembler using generator expression. It was not to be
committed.

CMake: Set compile defintions for supported toolchain at top level input source file ...

The compile defintions should always be added depending on the
selected toolchain.
mbed_set_toolchain_options() should only be called if a third-party
toolchain file has not been used as it has compile options that can
cause conflicts.

CMake: Fix Microlib selection (#13871) ...

As the assembler does not seem to recognise the request to the
linker to use microlib, remove that instruction.
Microlib is still used as the linker selects microlib as a result
of being explicitly asked to do so.

Replace PUBLIC to INTERFACE keyword

CMake: add mbed-os and mbed-baremetal targets ...

mbed-os consists of mbed-core and mbed-rtos
mbed-baremetal consists of mbed-core

The main change is for mbed-core. Changing from object library to be interface. This way it allows us to do the above to have 2 main targets for users to use.

This should be backward compatible change as mbed-os target we used contains the same files/options as previously set.

CMake: fix for Gcc Arm preprocessing linker file ...

A linker script needs symbols (stack size, app size, etc). They are basic values or defines. Not any array like or string like macros. We should filter these, as they are not valid anyway.

The other option to fix this would be to fix all the macros but I dont think it is needed as these config values won't be used in the linker script anyway.

Not allowed in ld files macros with spaces, like MACRO={0, 2, 3} or MACRO=(4 * 2000).

CMake: Add a function to generate executable artifacts with memap (#13695) ...

- Add linker option to generate map file for GCC_ARM and ARM toolchain
- Add mbed_generate_map_file function to call memap.py (parse the map
file).
- Add mbed_generate_executable function to generate executable artifacts with a memory map table

CMake: Fix TFM targets build ...

Add linking time pre-processor macro DOMAIN_NS
for TFM targets and TrustZone non secure targets.

CMake: Add support for printf lib selection

CMake: Add support for C lib selection ...

Configure the selected toolchain for the selected C library

CMake: Move modules under tools subdirectory