Merge 'cmake-native-type' branch: Use BUILD_SHARED_LIBS in CMake to specify the
build type of the libraries instead of APR_BUILD_SHARED and APR_BUILD_STATIC
options.

git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1920436 13f79535-47bb-0310-9956-ffa450edef68