configure: Add an explicit check and option for nvcc

The use of nvcc to compile cuda kernels is distinct from the use of
cuda sdk libraries and linking against those libraries. We have
previously not bothered to distinguish these two cases because all
the filters that used cuda kernels also used the sdk. In the following
changes, I'm going to remove the sdk dependency from those filters,
but we need a way to ensure that nvcc is present and functioning, and
also a way to explicitly disable its use so that the filters are not
built.
Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>

configure

@@ -321,6 +321,7 @@ External library support:
   The following libraries provide various hardware acceleration features:
   --disable-amf            disable AMF video encoding code [autodetect]
   --disable-audiotoolbox   disable Apple AudioToolbox code [autodetect]
+  --enable-cuda-nvcc       enable Nvidia CUDA compiler [no]
   --enable-cuda-sdk        enable CUDA features that require the CUDA SDK [no]
   --disable-cuvid          disable Nvidia CUVID support [autodetect]
   --disable-d3d11va        disable Microsoft Direct3D 11 video acceleration code [autodetect]
@@ -1001,6 +1002,10 @@ hostcc_o(){
     eval printf '%s\\n' $HOSTCC_O
 }
 
+nvcc_o(){
+    eval printf '%s\\n' $NVCC_O
+}
+
 test_cc(){
     log test_cc "$@"
     cat > $TMPC
@@ -1022,6 +1027,22 @@ test_objcc(){
     test_cmd $objcc -Werror=missing-prototypes $CPPFLAGS $CFLAGS $OBJCFLAGS "$@" $OBJCC_C $(cc_o $TMPO) $TMPM
 }
 
+test_nvcc(){
+    log test_nvcc "$@"
+    cat > $TMPCU
+    log_file $TMPCU
+    test_cmd $nvcc -ptx $NVCCFLAGS "$@" $NVCC_C $(nvcc_o $TMPO) $TMPCU
+}
+
+check_nvcc() {
+    log check_nvcc "$@"
+    test_nvcc <<EOF
+extern "C" {
+    __global__ void hello(unsigned char *data) {}
+}
+EOF
+}
+
 test_cpp(){
     log test_cpp "$@"
     cat > $TMPC
@@ -1806,6 +1827,7 @@ EXTRALIBS_LIST="
 "
 
 HWACCEL_LIBRARY_NONFREE_LIST="
+    cuda_nvcc
     cuda_sdk
     libnpp
 "
@@ -4238,6 +4260,7 @@ tmpfile TMPCPP .cpp
 tmpfile TMPE   $EXESUF
 tmpfile TMPH   .h
 tmpfile TMPM   .m
+tmpfile TMPCU  .cu
 tmpfile TMPO   .o
 tmpfile TMPS   .S
 tmpfile TMPSH  .sh
@@ -6087,6 +6110,7 @@ for func in $COMPLEX_FUNCS; do
 done
 
 # these are off by default, so fail if requested and not available
+enabled cuda_nvcc         && { check_nvcc || die "ERROR: failed checking for nvcc."; }
 enabled cuda_sdk          && require cuda_sdk cuda.h cuCtxCreate -lcuda
 enabled chromaprint       && require chromaprint chromaprint.h chromaprint_get_version -lchromaprint
 enabled decklink          && { require_headers DeckLinkAPI.h &&