build: adjust cmake invocation for export targets

This adjusts the cmake invocation for Foundation to use the export
targets rather than computing the locations by hand.

Author: compnerd

utils/build-script-impl

@@ -2916,6 +2916,7 @@ for host in "${ALL_HOSTS[@]}"; do
                     LIBDISPATCH_BUILD_ARGS=(
                       -DFOUNDATION_PATH_TO_LIBDISPATCH_SOURCE=${LIBDISPATCH_SOURCE_DIR}
                       -DFOUNDATION_PATH_TO_LIBDISPATCH_BUILD=${LIBDISPATCH_BUILD_DIR}
+                      -Ddispatch_DIR=${LIBDISPATCH_BUILD_DIR}/cmake/modules
                     )
                 else
                     LIBDISPATCH_BUILD_ARGS=( -DFOUNDATION_ENABLE_LIBDISPATCH=NO )
@@ -2924,20 +2925,22 @@ for host in "${ALL_HOSTS[@]}"; do
                 SWIFTC_BIN="$(build_directory_bin ${LOCAL_HOST} swift)/swiftc"
                 LLVM_BIN="$(build_directory_bin ${LOCAL_HOST} llvm)"
 
+                # NOTE(compnerd) the time has come to enable tests now
                 cmake_options=(
                   ${cmake_options[@]}
                   -DCMAKE_BUILD_TYPE:STRING=${FOUNDATION_BUILD_TYPE}
                   -DCMAKE_C_COMPILER:PATH=${LLVM_BIN}/clang
                   -DCMAKE_CXX_COMPILER:PATH=${LLVM_BIN}/clang++
-                  -DCMAKE_SWIFT_COMPILER:PATH=${SWIFTC_BIN}
                   -DCMAKE_Swift_COMPILER:PATH=${SWIFTC_BIN}
                   -DCMAKE_INSTALL_PREFIX:PATH=$(get_host_install_prefix ${host})
 
                   ${LIBICU_BUILD_ARGS[@]}
                   ${LIBDISPATCH_BUILD_ARGS[@]}
 
-                  # NOTE(compnerd) the time has come to enable tests now
                   -DENABLE_TESTING:BOOL=YES
+                  -DXCTest_DIR=$(build_directory ${host} xctest)/cmake/modules
+
+                  -DCMAKE_SWIFT_COMPILER:PATH=${SWIFTC_BIN}
                   -DFOUNDATION_PATH_TO_XCTEST_BUILD:PATH=$(build_directory ${host} xctest)
                 )