Minor changes to suppress compiler warnings in gcc

dlib/external/libjpeg/jccoefct.cpp

@@ -338,7 +338,7 @@ compress_first_pass (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
  */
 
 METHODDEF(int)
-compress_output (j_compress_ptr cinfo, JSAMPIMAGE input_buf)
+compress_output (j_compress_ptr cinfo, JSAMPIMAGE )//input_buf)
 {
   my_coef_ptr coef = (my_coef_ptr) cinfo->coef;
   JDIMENSION MCU_col_num;	/* index of current MCU within row */

dlib/external/libjpeg/jccolor.cpp

@@ -338,7 +338,7 @@ null_convert (j_compress_ptr cinfo,
  */
 
 METHODDEF(void)
-null_method (j_compress_ptr cinfo)
+null_method (j_compress_ptr )//cinfo)
 {
   /* no work needed */
 }

dlib/external/libjpeg/jcmarker.cpp

@@ -219,7 +219,7 @@ emit_dht (j_compress_ptr cinfo, int index, int is_ac)
 
 
 LOCAL(void)
-emit_dac (j_compress_ptr cinfo)
+emit_dac (j_compress_ptr )//cinfo)
 /* Emit a DAC marker */
 /* Since the useful info is so small, we want to emit all the tables in */
 /* one DAC marker.  Therefore this routine does its own scan of the table. */

dlib/external/libjpeg/jcsample.cpp

@@ -72,7 +72,7 @@ typedef my_downsampler * my_downsample_ptr;
  */
 
 METHODDEF(void)
-start_pass_downsample (j_compress_ptr cinfo)
+start_pass_downsample (j_compress_ptr )//cinfo)
 {
   /* no work for now */
 }