Compiler there is strict about the C/C++ call model
mixing in function variable assumptions.
Fixed by adding some 'extern "C"' and changing
'?' operator with 'if'.
Makefile.am:
add new API files to the check_abi rule,
remove duplicates
client/CMakeLists.txt:
now a client can use dlopen too
client/Makefile.am:
be csh-friendly
include/my_global.h:
add dummy plugs for dlopen and co.
for the code that needs them to work in static builds
mysys/Makefile.am:
be csh-friendly
plugin/auth/dialog.c:
typo fixed
