try to work around mscv warning-turned-error

warning C4701: potentially uninitialized local variable 'r_' used

x86/clmul.h

@@ -34,6 +34,7 @@
 #define SIMDE_X86_CLMUL_H
 
 #include "avx512/set.h"
+#include "avx512/setzero.h"
 
 #if !defined(SIMDE_X86_PCLMUL_NATIVE) && defined(SIMDE_ENABLE_NATIVE_ALIASES)
 #  define SIMDE_X86_PCLMUL_ENABLE_NATIVE_ALIASES
@@ -318,6 +319,9 @@ simde_mm512_clmulepi64_epi128 (simde__m512i a, simde__m512i b, const int imm8)
     b_ = simde__m512i_to_private(b),
     r_;
 
+  #if defined(HEDLEY_MSVC_VERSION)
+    r_ = simde__m512i_to_private(simde_mm512_setzero_si512());
+  #endif
   #if SIMDE_NATURAL_VECTOR_SIZE_LE(256)
     switch (imm8 & 0x11) {
       case 0x00: