Require 64-bit builds on x86 to use CRC32 hardware acceleration

32-bit builds with SSE 4.2 do exist, and these builds do not work
without this patch.

PiperOrigin-RevId: 499498979
Change-Id: I0ade09068804655652c07d0f1ef13554464a1558

absl/crc/internal/crc32_x86_arm_combined_simd.h

@@ -25,8 +25,10 @@
 // We define a translation layer for both x86 and ARM for the ease of use and
 // most performance gains.
 
-// We need CRC (part of SSE 4.2) and PCLMULQDQ instructions.
-#if defined(__SSE4_2__) && defined(__PCLMUL__)
+// This implementation requires 64-bit CRC instructions (part of SSE 4.2) and
+// PCLMULQDQ instructions. 32-bit builds with SSE 4.2 do exist, so the
+// __x86_64__ condition is necessary.
+#if defined(__x86_64__) && defined(__SSE4_2__) && defined(__PCLMUL__)
 
 #include <x86intrin.h>
 #define ABSL_CRC_INTERNAL_HAVE_X86_SIMD