Fix CMake to support being a subproject (#29)

Author: wgtmac

CMakeLists.txt

@@ -46,7 +46,7 @@ set(ICEBERG_INSTALL_BINDIR "${CMAKE_INSTALL_BINDIR}")
 set(ICEBERG_INSTALL_INCLUDEDIR "${CMAKE_INSTALL_INCLUDEDIR}")
 set(ICEBERG_INSTALL_CMAKEDIR "${CMAKE_INSTALL_LIBDIR}/cmake")
 set(ICEBERG_INSTALL_DOCDIR "share/doc/${PROJECT_NAME}")
-set(ICEBERG_INCLUDES "${CMAKE_SOURCE_DIR}/src" "${CMAKE_BINARY_DIR}/src")
+set(ICEBERG_INCLUDES "${PROJECT_BINARY_DIR}/src" "${PROJECT_SOURCE_DIR}/src")
 
 if(WIN32 AND NOT MINGW)
   set(MSVC_TOOLCHAIN TRUE)
@@ -55,8 +55,8 @@ else()
 endif()
 
 include(CMakeParseArguments)
-include(BuildUtils)
-include(ThirdpartyToolchain)
+include(IcebergBuildUtils)
+include(IcebergThirdpartyToolchain)
 include(GenerateExportHeader)
 
 add_subdirectory(src)

cmake_modules/BuildUtils.cmake renamed to cmake_modules/IcebergBuildUtils.cmake

@@ -92,10 +92,6 @@ function(resolve_arrow_dependency)
                        Arrow
                        CONFIG)
 
-  # Add Arrow cmake modules to the search path
-  list(PREPEND CMAKE_MODULE_PATH
-       ${CMAKE_CURRENT_BINARY_DIR}/_deps/arrow-src/cpp/cmake_modules)
-
   fetchcontent_makeavailable(Arrow)
 
   if(arrow_SOURCE_DIR)