Include <bit> header when std::count{r,l}_zero is used

Needed for compilation with older libc++ releases

src/shader_recompiler/backend/spirv/emit_spirv_atomic.cpp

@@ -2,6 +2,8 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <bit>
+
 #include "shader_recompiler/backend/spirv/emit_spirv.h"
 #include "shader_recompiler/backend/spirv/emit_spirv_instructions.h"
 #include "shader_recompiler/backend/spirv/spirv_emit_context.h"

src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <bit>
 #include <tuple>
 #include <utility>
 

src/shader_recompiler/backend/spirv/spirv_emit_context.cpp

@@ -4,6 +4,7 @@
 
 #include <algorithm>
 #include <array>
+#include <bit>
 #include <climits>
 
 #include <boost/container/static_vector.hpp>