Remove #undefs for formerly forbidden system functions

The macros forbidding the system functions no longer exist, obviating
the need for the #undefs.

compat/getopt.c

@@ -38,8 +38,6 @@ static int optind = 1;
 static int optopt;
 static char *optarg;
 
-#undef fprintf
-
 static int getopt(int argc, char *argv[], char *opts)
 {
     static int sp = 1;

libavcodec/dct-test.c

@@ -47,8 +47,6 @@
 #include "x86/idct_xvid.h"
 #include "dctref.h"
 
-#undef printf
-
 // BFIN
 void ff_bfin_idct(int16_t *block);
 void ff_bfin_fdct(int16_t *block);

libavcodec/dvbsubdec.c

@@ -34,8 +34,6 @@
 #define cm (ff_cropTbl + MAX_NEG_CROP)
 
 #ifdef DEBUG
-#undef fprintf
-#undef perror
 #if 0
 static void png_save(const char *filename, uint8_t *bitmap, int w, int h,
                      uint32_t *rgba_palette)

libavcodec/dvdsubdec.c

@@ -439,9 +439,6 @@ static int find_smallest_bounding_rectangle(AVSubtitle *s)
 }
 
 #ifdef DEBUG
-#undef fprintf
-#undef perror
-#undef exit
 static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,
                      uint32_t *rgba_palette)
 {