Replace boost::optional with std::optional where possible

src/video_core/shader/shader_jit_x64_compiler.cpp

@@ -754,7 +754,7 @@ void JitShader::Compile_LOOP(Instruction instr) {
     sub(LOOPCOUNT, 1);           // Increment loop count by 1
     jnz(l_loop_start);           // Loop if not equal
     L(*loop_break_label);
-    loop_break_label = boost::none;
+    loop_break_label.reset();
 
     looping = false;
 }

src/video_core/shader/shader_jit_x64_compiler.h

@@ -6,9 +6,9 @@
 
 #include <array>
 #include <cstddef>
+#include <optional>
 #include <utility>
 #include <vector>
-#include <boost/optional.hpp>
 #include <nihstro/shader_bytecode.h>
 #include <xbyak.h>
 #include "common/bit_set.h"
@@ -123,7 +123,7 @@ private:
 
     /// Label pointing to the end of the current LOOP block. Used by the BREAKC instruction to break
     /// out of the loop.
-    boost::optional<Xbyak::Label> loop_break_label;
+    std::optional<Xbyak::Label> loop_break_label;
 
     /// Offsets in code where a return needs to be inserted
     std::vector<unsigned> return_offsets;