tidy: Ignore parentheses in complex expression in mythmpeg2 library.

Many of these warnings are in the middle of complex macros, and tidy
can't point out exactly where the additions need to be made.  Leave
them alone for now, especially since this is imported code that might
go away if mythtranscode is ever rewritten to use FFmpeg.

https://clang.llvm.org/extra/clang-tidy/checks/readability/math-missing-parentheses.html

mythtv/libs/libmythmpeg2/idct_mmx.c

@@ -38,6 +38,7 @@
 #define round(bias) ((int)(((bias)+0.5) * (1<<ROW_SHIFT)))
 #define rounder(bias) {round (bias), round (bias)}
 
+/* NOLINTBEGIN(readability-math-missing-parentheses) */
 
 #if 0
 /* C row IDCT - its just here to document the MMXEXT and MMX versions */
@@ -819,4 +820,6 @@ void mpeg2_idct_mmx_init (void)
     }
 }
 
+/* NOLINTEND(readability-math-missing-parentheses) */
+
 #endif

mythtv/libs/libmythmpeg2/slice.c

@@ -922,6 +922,7 @@ static inline void slice_non_intra_DCT (mpeg2_decoder_t * const decoder,
     mpeg2_idct_add (last, decoder->DCTblock, dest, stride);
 }
 
+/* NOLINTBEGIN(readability-math-missing-parentheses) */
 #define MOTION_420(table,ref,motion_x,motion_y,size,y)			      \
     pos_x = 2 * decoder->offset + (motion_x);				      \
     pos_y = 2 * decoder->v_offset + (motion_y) + 2 * (y);		      \
@@ -1200,6 +1201,7 @@ static inline void slice_non_intra_DCT (mpeg2_decoder_t * const decoder,
 	      (ref)[1] + offset, decoder->stride, 16);			      \
     (table)[4] (decoder->dest[2] + decoder->offset,			      \
 	      (ref)[2] + offset, decoder->stride, 16)
+/* NOLINTEND(readability-math-missing-parentheses) */
 
 #define bit_buf (decoder->bitstream_buf)
 #define bits (decoder->bitstream_bits)