Increment major version number due to backwards incompatibility

Bump SO version and fix some const values

cmake: Fix libbtbb.pc.in.

The @prefix@, @exec_prefix@, @libdir@ and @includedir@ variables are not
set by cmake. Set the values in the libbtbb.pc.in file by including the
GNUInstallDirs.cmake file i

cmake: Fix libbtbb.pc.in.

The @prefix@, @exec_prefix@, @libdir@ and @includedir@ variables are not
set by cmake. Set the values in the libbtbb.pc.in file by including the
GNUInstallDirs.cmake file in CMakeLists.txt. This creates the
CMAKE_INSTALL_LIBDIR and CMAKE_INSTALL_INCLUDEDIR variables.

This change allows user to configure for installing into non-standard
locations as such:

mkdir build
cd build
cmake -DCMAKE_INSTALL_PREFIX=$HOME/local ..

show more ...

Fix pkgconfig install path

Add pkgconfig file

Build libbtbb and pcaptools using cmake