pydoc: Fixed mix of python2/3 modules with pydoc

The pydoc target copies python binaries and modules to pyupm.  Since the
find command didn't make a distinction between python2/3 modules, a mix
of each could end up in pyupm.  If sphinx runs under a mismatching
interpreter (mismatching against the python binaries) the build would
fail with load errors

    * Only copy python2 modules (and binaries) to pyupm directory
    * Explicitly run the sphinx tools w/python2
    * Removed doc dependency to each library target (not needed).

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/CMakeLists.txt

@@ -510,13 +510,6 @@ function(upm_swig_java)
   endif (NOT ";${JAVASWIG_BLACKLIST};" MATCHES ";${libname};")
 endfunction(upm_swig_java)
 
-macro(upm_doxygen)
-  if (DOXYGEN_FOUND)
-    set (CMAKE_SWIG_FLAGS -DDOXYGEN=${DOXYGEN_FOUND})
-    add_dependencies (doc ${libname})
-  endif ()
-endmacro(upm_doxygen)
-
 if (NPM)
 add_custom_target (npmpkg)
 add_custom_command (TARGET npmpkg POST_BUILD COMMAND echo "Creating NPM tarballs..."
@@ -759,11 +752,6 @@ function(upm_module_init)
   set_target_properties(${libname} PROPERTIES PKG_EXT_REQ_LIBS "${reqlibname}")
   set_target_properties(${libname} PROPERTIES TARGET_BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}")
 
-  # Skip doxygen run on C (for now)
-  if (BUILDDOC AND NOT IS_C_LIBRARY)
-    upm_doxygen()
-  endif()
-
   # Install target library to lib dir
   install (TARGETS ${libname}
       DESTINATION ${LIB_INSTALL_DIR}