[Minor] Limit sse41 code to sse41 and x86_64

contrib/fastutf8/CMakeLists.txt

 SET(UTFSRC ${CMAKE_CURRENT_SOURCE_DIR}/fastutf8.c)
-IF(HAVE_AVX2)
+IF(HAVE_AVX2 AND "${ARCH}" STREQUAL "x86_64")
     SET(UTFSRC ${UTFSRC} ${CMAKE_CURRENT_SOURCE_DIR}/avx2.c)
     MESSAGE(STATUS "UTF8: AVX2 support is added")
 ENDIF()
-IF(HAVE_SSE41)
+IF(HAVE_SSE41 AND "${ARCH}" STREQUAL "x86_64")
     SET(UTFSRC ${UTFSRC} ${CMAKE_CURRENT_SOURCE_DIR}/sse41.c)
     MESSAGE(STATUS "UTF8: SSE41 support is added")
 ENDIF()
 
-CONFIGURE_FILE(platform_config.h.in platform_config.h)
-
 ADD_LIBRARY(rspamd-fastutf8 STATIC ${UTFSRC})

contrib/fastutf8/fastutf8.c

  */
 
 #include "fastutf8.h"
-#include "platform_config.h"
+#include "libcryptobox/platform_config.h"
 
 
 /*
 }
 
 /* Prototypes */
-#ifdef HAVE_SSSE3
+#if defined(HAVE_SSE41) && defined(__x86_64__)
 extern off_t rspamd_fast_utf8_validate_sse41 (const unsigned char *data, size_t len);
 #endif
-#ifdef HAVE_AVX2
+#if defined(HAVE_AVX2) && defined(__x86_64__)
 extern off_t rspamd_fast_utf8_validate_avx2 (const unsigned char *data, size_t len);
 #endif
 
 void
 rspamd_fast_utf8_library_init (unsigned flags)
 {
-#ifdef HAVE_SSSE3
+#if defined(HAVE_SSE41) && defined(__x86_64__)
 	if (flags & RSPAMD_FAST_UTF8_FLAG_SSE41) {
 		validate_func = rspamd_fast_utf8_validate_sse41;
 	}
 #endif
-#ifdef HAVE_AVX2
+#if defined(HAVE_AVX2) && defined(__x86_64__)
 	if (flags & RSPAMD_FAST_UTF8_FLAG_AVX2) {
 		validate_func = rspamd_fast_utf8_validate_avx2;
 	}

contrib/fastutf8/platform_config.h.in

-#ifndef PLATFORM_H_CONFIG
-#define PLATFORM_H_CONFIG
-
-#define ARCH "${ARCH}"
-#define CMAKE_ARCH_${ARCH} 1
-
-#ifdef __x86_64__
-#cmakedefine HAVE_AVX2	1
-#cmakedefine HAVE_SSE41	1
-#cmakedefine HAVE_SSSE3	1
-#endif
-
-#endif