* Add mbedtls as a submodule
Checked out on branch mbedtls-2.28
* Add mbedtls to pico-sdk
Link your code to pico_lwip_mbedtls and pico_mbedtls.
See tls_client example in pico-examples
Fixes https://github.com/raspberrypi/pico-sdk/issues/893
* fix __force_inline for different GCC versions in cpp mode (the affected versions are different from c mode), and build kitchsink.c as a cpp file too for testing
* silly bug in host platform.h
* Add pico_bootsel_via_double_reset library, fix#87
* pico_bootsel_via_double_reset: remove unnecessary library guard, fix subdirectory ordering
* Fix C type used as PICO_CONFIG type
In C, func() is a function taking an unspecified number of arguments,
vs func(void) a function taking no arguments. In C++ both forms indicate
"no arguments."
Update these headers to use the (void) form, which is correct in both
languages and avoids complaints when -Wstrict-prototypes is specified.
