do not register handlers for fastmem if fastmem is disabled

Signed-off-by: lizzie <lizzie@eden-emu.dev>

src/dynarmic/src/dynarmic/backend/exception_handler_posix.cpp

@@ -57,7 +57,7 @@ class SigHandler {
 public:
     SigHandler() noexcept {
         signal_stack_size = std::max<size_t>(SIGSTKSZ, 2 * 1024 * 1024);
-        signal_stack_memory = mmap(nullptr, signal_stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+        signal_stack_memory = std::malloc(signal_stack_size);
 
         stack_t signal_stack{};
         signal_stack.ss_sp = signal_stack_memory;
@@ -89,7 +89,7 @@ public:
     }
 
     ~SigHandler() noexcept {
-        munmap(signal_stack_memory, signal_stack_size);
+        std::free(signal_stack_memory);
     }
 
     void AddCodeBlock(u64 offset, CodeBlockInfo cbi) noexcept {

src/dynarmic/src/dynarmic/backend/x64/a32_emit_x64.cpp

@@ -81,8 +81,10 @@ FP::FPCR A32EmitContext::FPCR(bool fpcr_controlled) const {
 }
 
 A32EmitX64::A32EmitX64(BlockOfCode& code, A32::UserConfig conf, A32::Jit* jit_interface)
-        : EmitX64(code), conf(std::move(conf)), jit_interface(jit_interface) {
-    GenFastmemFallbacks();
+    : EmitX64(code), conf(std::move(conf)), jit_interface(jit_interface) {
+    if (conf.fastmem_pointer)
+        GenFastmemFallbacks();
+    //
     GenTerminalHandlers();
     code.PreludeComplete();
     ClearFastDispatchTable();

src/dynarmic/src/dynarmic/backend/x64/a64_emit_x64.cpp

@@ -54,9 +54,11 @@ FP::FPCR A64EmitContext::FPCR(bool fpcr_controlled) const {
 }
 
 A64EmitX64::A64EmitX64(BlockOfCode& code, A64::UserConfig conf, A64::Jit* jit_interface)
-        : EmitX64(code), conf(conf), jit_interface{jit_interface} {
+    : EmitX64(code), conf(conf), jit_interface{jit_interface} {
+    if (conf.fastmem_pointer)
+        GenFastmemFallbacks();
+    //
     GenMemory128Accessors();
-    GenFastmemFallbacks();
     GenTerminalHandlers();
     code.PreludeComplete();
     ClearFastDispatchTable();