d3d12: add missing cmath includes

If we want to use the std:: version of the math functions, we need to
include <cmath>.

Fixes: b171a6baa2 ("d3d12: Add video encode implementation of pipe_video_codec")
Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16636>

src/gallium/drivers/d3d12/d3d12_video_dec_h264.cpp

@@ -24,6 +24,8 @@
 #include "d3d12_video_dec.h"
 #include "d3d12_video_dec_h264.h"
 
+#include <cmath>
+
 void
 d3d12_video_decoder_refresh_dpb_active_references_h264(struct d3d12_video_decoder *pD3D12Dec)
 {

src/gallium/drivers/d3d12/d3d12_video_enc.cpp

@@ -48,6 +48,8 @@
 #include "util/u_memory.h"
 #include "util/u_video.h"
 
+#include <cmath>
+
 /**
  * flush any outstanding command buffers to the hardware
  * should be called before a video_buffer is acessed by the gallium frontend again

src/gallium/drivers/d3d12/d3d12_video_enc_h264.cpp

@@ -27,6 +27,8 @@
 #include "d3d12_screen.h"
 #include "d3d12_format.h"
 
+#include <cmath>
+
 void
 d3d12_video_encoder_update_current_rate_control_h264(struct d3d12_video_encoder *pD3D12Enc,
                                                      pipe_h264_enc_picture_desc *picture)

src/gallium/drivers/d3d12/d3d12_video_encoder_bitstream_builder_h264.cpp

@@ -23,6 +23,8 @@
 
 #include "d3d12_video_encoder_bitstream_builder_h264.h"
 
+#include <cmath>
+
 inline H264_SPEC_PROFILES
 Convert12ToSpecH264Profiles(D3D12_VIDEO_ENCODER_PROFILE_H264 profile12)
 {