liblzma: CRC CLMUL: Omit is_arch_extension_supported() when not needed

On E2K the function compiles only due to compiler emulation but the
function is never used. It's cleaner to omit the function when it's
not needed even though it's a "static inline" function.

Thanks to Ilya Kurdyukov.

(cherry picked from commit 30a2d5d510)

src/liblzma/check/crc_x86_clmul.h

@@ -385,6 +385,9 @@ crc64_arch_optimized(const uint8_t *buf, size_t size, uint64_t crc)
 #endif // BUILDING_CRC64_CLMUL
 
 
+// Even though this is an inline function, compile it only when needed.
+// This way it won't appear in E2K builds at all.
+#if defined(CRC32_GENERIC) || defined(CRC64_GENERIC)
 // Inlining this function duplicates the function body in crc32_resolve() and
 // crc64_resolve(), but this is acceptable because this is a tiny function.
 static inline bool
@@ -426,3 +429,4 @@ is_arch_extension_supported(void)
 	// code as is it only reads a variable set at startup but a few bytes
 	// doesn't matter here.
 }
+#endif