Fix #786 - 3.05 linkage fails on macOS Sierra with --enable-opencl

Also needed for 4.00.

api/Makefile.am

@@ -46,7 +46,7 @@ endif
 libtesseract_api_la_SOURCES = baseapi.cpp capi.cpp renderer.cpp pdfrenderer.cpp
 
 lib_LTLIBRARIES += libtesseract.la
-libtesseract_la_LDFLAGS = $(LEPTONICA_LIBS)
+libtesseract_la_LDFLAGS = $(LEPTONICA_LIBS) $(OPENCL_LDFLAGS)
 libtesseract_la_SOURCES =
 # Dummy C++ source to cause C++ linking.
 # see http://www.gnu.org/s/hello/manual/automake/Libtool-Convenience-Libraries.html#Libtool-Convenience-Libraries