configure: Fix OpenCL includes on systems with only CL/cl.h.
diff --git a/configure.ac b/configure.ac
index 773a727..5ea8356 100644
--- a/configure.ac
+++ b/configure.ac
@@ -69,7 +69,7 @@
 AC_ARG_WITH(openal,    AS_HELP_STRING([--without-openal],[do not use OpenAL]),
             [if test "x$withval" = "xno"; then ac_cv_header_AL_al_h=no; ac_cv_header_OpenAL_al_h=no; fi])
 AC_ARG_WITH(opencl,    AS_HELP_STRING([--without-opencl],[do not use OpenCL]),
-            [if test "x$withval" = "xno"; then ac_cv_header_CL_opencl_h=no; ac_cv_header_OpenCL_opencl_h=no; fi])
+            [if test "x$withval" = "xno"; then ac_cv_header_CL_cl_h=no; ac_cv_header_OpenCL_opencl_h=no; fi])
 AC_ARG_WITH(opengl,    AS_HELP_STRING([--without-opengl],[do not use OpenGL]))
 AC_ARG_WITH(openssl,   AS_HELP_STRING([--without-openssl],[do not use OpenSSL]),
             [if test "x$withval" = "xno"; then ac_cv_header_openssl_err_h=no; ac_cv_header_openssl_ssl_h=no; fi])
@@ -370,7 +370,7 @@
 	AL/al.h \
 	AudioToolbox/AudioConverter.h \
 	AudioUnit/AudioUnit.h \
-	CL/opencl.h \
+	CL/cl.h \
 	Carbon/Carbon.h \
 	CoreAudio/CoreAudio.h \
 	DiskArbitration/DiskArbitration.h \
@@ -1107,7 +1107,7 @@
 to install ${notice_platform}development packages of Xlib/Xfree86 at the very least.])
 
 dnl **** Check for OpenCL ****
-if test "$ac_cv_header_CL_opencl_h" = "yes"
+if test "$ac_cv_header_CL_cl_h" = "yes"
 then
     AC_CHECK_LIB(OpenCL,clGetPlatformInfo,[AC_SUBST(LIBOPENCL,["-lOpenCL"])])
 fi