It uses a dedicated LIBVVP_SOVERSION specified in onfigure.ac
for the SONAME and full library version.
For linking, a pkg-config file is generated, and when building on
Windows, an import library is created that can be used with both
GCC and MSVC compilers.
On non-Windows platforms, all object files are compiled with -fPIC
to ensure compatibility with shared libraries.
On Windows use 'lib' prefix for library name with MinGW compiler
only. Other compiler like MSVC normally are not using any library
prefix.
With this commit the build rules for the vpp executable has been
cleaned too because the complex structure of the manually created
Makefile.in made it very difficult to extract specific parts of
them.