Fix cross-compilation

Use the cross-compiler and not the host version.

Patch sent upstream:
https://github.com/notspiff/screensavers.rsxs/pull/5

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>

diff -uNr screensavers.rsxs-195e0ec3fbbcb2ee2012cd560e42d05167f0f259.org/CMakeLists.txt screensavers.rsxs-195e0ec3fbbcb2ee2012cd560e42d05167f0f259/CMakeLists.txt
--- screensavers.rsxs-195e0ec3fbbcb2ee2012cd560e42d05167f0f259.org/CMakeLists.txt	2015-03-19 12:20:23.000000000 +0100
+++ screensavers.rsxs-195e0ec3fbbcb2ee2012cd560e42d05167f0f259/CMakeLists.txt	2015-07-19 20:26:16.660481032 +0200
@@ -33,6 +33,11 @@
                     ${PROJECT_SOURCE_DIR}/${rsxs_dir}/src/skyrocket
                     ${PROJECT_SOURCE_DIR}/${rsxs_dir}/src/solarwinds)
                         
+
+get_filename_component( COMPILER_FILENAME "${CMAKE_C_COMPILER}" NAME )
+string( REGEX REPLACE "-[^-]+$" ""
+        TOOLCHAIN_NAME "${COMPILER_FILENAME}" )
+
 include(ExternalProject)
 set(update_command "")
 if(BOOTSTRAP_IN_TREE OR NOT DEFINED BOOTSTRAP_IN_TREE)
@@ -46,8 +51,11 @@
   endif()
 endif()
 externalproject_add(rsxs SOURCE_DIR ${PROJECT_SOURCE_DIR}/${rsxs_dir}
-                    CONFIGURE_COMMAND ${configure_start}
+                    CONFIGURE_COMMAND gl_cv_func_gettimeofday_clobber=no ac_cv_type__Bool=yes
+                                      ac_cv_func_malloc_0_nonnull=yes
+                                      ${configure_start}
                                       --prefix=<INSTALL_DIR>
+                                      --host=${TOOLCHAIN_NAME}
                                       --without-xscreensaver
                                       --disable-cyclone
                                       --disable-euphoria