Consistently place C++ use of extern "C" after all include directives,
within the negative branch of _ASMLANGUAGE if used.
Background from issue #17997:
Declarations that use C linkage should be placed within extern "C"
so the language linkage is correct when the header is included by
a C++ compiler.
Similarly #include directives should be outside the extern "C" to
ensure the language-specific default linkage is applied to any
declarations provided by the included header.
See: https://en.cppreference.com/w/cpp/language/language_linkage
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
A few of these headers are currently empty and provided to avoid
compiler errors when building existing software.
This set of headers is what is required to build
https://github.com/open62541/open62541 with Zephyr.
Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>