avcodec/mathops: Set hidden visibility where advantageous

It is advantageous for ff_crop_tab, as the base pointer used to
access this table is not the first element of it. But the real
base pointer is still at a constant offset from the code/the GOT
and can therefore be accessed relative to the instruction pointer
(if supported by the arch) or relative to the GOT; without this,
one has to first load address of ff_crop_tab (potentially via
the GOT) and then offset manually (which is what the earlier code
did).

Reviewed-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/mathops.h

@@ -24,6 +24,7 @@
 
 #include <stdint.h>
 
+#include "libavutil/attributes_internal.h"
 #include "libavutil/common.h"
 #include "config.h"
 
@@ -32,7 +33,7 @@
 extern const uint32_t ff_inverse[257];
 extern const uint8_t ff_log2_run[41];
 extern const uint8_t ff_sqrt_tab[256];
-extern const uint8_t ff_crop_tab[256 + 2 * MAX_NEG_CROP];
+extern const uint8_t attribute_visibility_hidden ff_crop_tab[256 + 2 * MAX_NEG_CROP];
 extern const uint8_t ff_zigzag_direct[64];
 extern const uint8_t ff_zigzag_scan[16+1];