Properly handle when the build directory has spaces in its name.

CMake/GeneratePkgConfig.cmake

@@ -5,12 +5,13 @@
 # And our goal in this file is to generate/configure mlpack.pc.
 
 # First, we need to extract the version string.
-if (NOT EXISTS "${MLPACK_SOURCE_DIR}/mlpack/core/util/version.hpp")
+if (NOT EXISTS "${CMAKE_BINARY_DIR}/include/mlpack/core/util/version.hpp")
   message(FATAL_ERROR "Cannot open "
-      "${MLPACK_SOURCE_DIR}/mlpack/core/util/version.hpp to extract version!")
+      "${CNAKE_BINARY_DIR}/include/mlpack/core/util/version.hpp to extract "
+      "version!")
 endif ()
 
-file(READ "${MLPACK_SOURCE_DIR}/mlpack/core/util/version.hpp"
+file(READ "${CMAKE_BINARY_DIR}/include/mlpack/core/util/version.hpp"
     VERSION_HPP_CONTENTS)
 string(REGEX REPLACE ".*#define MLPACK_VERSION_MAJOR ([0-9]+).*" "\\1"
     MLPACK_VERSION_MAJOR "${VERSION_HPP_CONTENTS}")

CMakeLists.txt

@@ -534,10 +534,10 @@ if (PKG_CONFIG_FOUND)
 
   add_custom_target(pkgconfig ALL
       ${CMAKE_COMMAND}
-          -D MLPACK_SOURCE_DIR="${CMAKE_BINARY_DIR}/include/"
           -P "${CMAKE_CURRENT_SOURCE_DIR}/CMake/GeneratePkgConfig.cmake"
       DEPENDS mlpack_headers
-      COMMENT "Generating mlpack.pc (pkg-config) file.")
+      COMMENT "Generating mlpack.pc (pkg-config) file."
+      VERBATIM)
 
   # Do we need a different directory?
   install(FILES ${CMAKE_CURRENT_BINARY_DIR}/lib/pkgconfig/mlpack.pc