mbedtls 3.x support

[andyli]

A few distros pumped their mbedtls 2.x to 3.x (see mbedtls on repology) and it's beginning to affect us - openSUSE neko package build is failing.

Hopefully we can support both 2.x and 3.x, by the use of C preprocessing macros.

[alucryd]

Same thing with archlinux. We made a compat package for the time being (with headers in /usr/include/mbedtls2, and libs in /usr/lib/mbedtls2), but the dune build system does not respect CFLAGS, even though they've been added as per dune's documentation.

(include_subdirs no)

(library
	(name mbedtls)
	(foreign_stubs
		(language c)
		(names mbedtls_stubs)
		(flags -I/usr/include/mbdetls2))
	(c_library_flags (-L/usr/lib/mbedtls2))
	(wrapped false)
)

[kLabz]

Same thing with archlinux. We made a compat package for the time being (with headers in /usr/include/mbedtls2, and libs in /usr/lib/mbedtls2), but the dune build system does not respect CFLAGS, even though they've been added as per dune's documentation.

(include_subdirs no)

(library
	(name mbedtls)
	(foreign_stubs
		(language c)
		(names mbedtls_stubs)
		(flags -I/usr/include/mbdetls2))
	(c_library_flags (-L/usr/lib/mbedtls2))
	(wrapped false)
)

Thanks! I managed to get it working locally on arch with mbedtls2 package and this libs/mbedtls/dune:

(include_subdirs no)

(library
        (name mbedtls)
        (foreign_stubs
                (language c)
                (names mbedtls_stubs)
                (flags -I/usr/include/mbdetls2 -fPIC))
        (c_library_flags (-L/usr/lib/mbedtls2))
        (wrapped false)
)