Support compiling and running either _runme.c or _runme.cxx files for
the given test (but not both).
Add a simple C++ test file to check that it actually works.
There doesn't seem to be any reason for using it rather than just
returning from main() as usual, and it provokes warnings about
implicitly declared function when compiling them.
The proxy layer, and all the extra complexity associated with it, seemed to be
only necessary in order to try to allow using the same name for the wrapped
global functions as were used for them in the original C or C++ code being
wrapped. However this could simply never work in all cases, notably it didn't
work at all when using ELF shared libraries under Unix as the functions with
the same name defined in the main program were interposed and replaced the
functions defined in the shared library, meaning that the proxy function foo()
called wrapper function _wrap_foo() which called back into proxy function
foo() itself again, resulting in guaranteed stack overflow. The only possible
way to fix this would be to use "protected" ELF visibility for the original
functions, but this is not always possible (e.g. if the sources of the
original library are not available) and not simple even when it is and,
besides, protected visibility has its own problems -- notably by making it
impossible to hook the library functions when you actually want to do it.
Besides, proxy-based approach simply couldn't work at all when using static
linking as it resulted in two copies of the function with the same name
Most importantly, however, the main task of this module is to wrap C++
classes, not C functions, and renaming them in the wrapper is not necessary at
all in this case as there is no conflict with the original names in this case.
So simply drop the idea of generating a separate proxy header and generate a
header declaring the functions declared in the wrapper instead and, also, do
not give them "_wrap_" prefix whenever possible, i.e. only do it for the
global functions.
This simplifies SWIG code itself and makes it simpler to use its output as
it's not necessary to link both with the wrapper (dynamically) and with the
proxy (statically) and it's not enough to link with the wrapper only and it
can be done in any way (i.e. either statically or dynamically).
As a side effect of this change, Swig_name_proxy() is not necessary any more
and was removed, eliminating the only difference with the master branch in any
source file other than c.cxx itself.
Make "make check-c-examples" perform the correct build commands, e.g. not link
the proxy code into the shared library as this can't work because it defines
the same functions that are already present in it.
Also fix the c_xxx targets to work when SWIG is built in a separate build
directory.
Finally, simplify them by removing the unnecessary variables.
Notice that std_vector example still doesn't build, but at least now it is due
to a real problem in the C module and not makefile bugs.
