Work around OpenCL loader defining DllMain in static build

Author: BtbN

scripts.d/45-opencl.sh

@@ -22,6 +22,8 @@ ffbuild_dockerbuild() {
     cd loader
     mkdir build && cd build
 
+    export CFLAGS="$CFLAGS -DDllMain=OpenCL_DllMain"
+
     cmake -DCMAKE_TOOLCHAIN_FILE="$FFBUILD_CMAKE_TOOLCHAIN" -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="$FFBUILD_PREFIX" \
         -DOPENCL_ICD_LOADER_HEADERS_DIR="$FFBUILD_DESTPREFIX"/include -DOPENCL_ICD_LOADER_BUILD_SHARED_LIBS=OFF \
         -DOPENCL_ICD_LOADER_DISABLE_OPENCLON12=ON -DOPENCL_ICD_LOADER_PIC=ON \