configure: Allow linking to CUDA dynamically instead of dlopen()ing it at runtime

This currently doesn't do anything, but will be used later for hwaccel
filters and libavutil.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

configure

@@ -196,6 +196,7 @@ Individual component options:
 External library support:
   --enable-avisynth        enable reading of AviSynth script files [no]
   --disable-bzlib          disable bzlib [autodetect]
+  --enable-cuda            enable dynamically linked CUDA [no]
   --enable-chromaprint     enable audio fingerprinting with chromaprint [no]
   --enable-fontconfig      enable fontconfig, useful for drawtext filter [no]
   --enable-frei0r          enable frei0r video filtering [no]
@@ -1426,6 +1427,7 @@ EXTERNAL_LIBRARY_LIST="
     bzlib
     chromaprint
     crystalhd
+    cuda
     decklink
     frei0r
     gcrypt
@@ -4883,6 +4885,7 @@ die_license_disabled gpl libxavs
 die_license_disabled gpl libxvid
 die_license_disabled gpl x11grab
 
+die_license_disabled nonfree cuda
 die_license_disabled nonfree libfaac
 die_license_disabled nonfree nvenc
 enabled gpl && die_license_disabled_gpl nonfree libfdk_aac
@@ -5452,6 +5455,7 @@ enabled avfoundation_indev && { check_lib2 CoreGraphics/CoreGraphics.h CGGetActi
 enabled avisynth          && { { check_lib2 "windows.h" LoadLibrary; } ||
                                { check_lib2 "dlfcn.h" dlopen -ldl; } ||
                                die "ERROR: LoadLibrary/dlopen not found for avisynth"; }
+enabled cuda              && check_lib cuda.h cuInit -lcuda
 enabled chromaprint       && require chromaprint chromaprint.h chromaprint_get_version -lchromaprint
 enabled decklink          && { check_header DeckLinkAPI.h || die "ERROR: DeckLinkAPI.h header not found"; }
 enabled frei0r            && { check_header frei0r.h || die "ERROR: frei0r.h header not found"; }