Use ABSL_INTERNAL_HAS_SSE2 instead of __SSE2__

This ensures that emmintrin.h is included with clang-cl. Otherwise, errors like
this occur:
.../absl/container/internal/raw_hash_set.h(536,8): error: unknown type name '__m128i'
inline __m128i _mm_cmpgt_epi8_fixed(__m128i a, __m128i b) {

This aligns the include ifdef guards and the guards that use the provided APIs.
The includes are also reordered, so they appear after the config header which
provides the internal macro values.

PiperOrigin-RevId: 456530271
Change-Id: I86dfd0022fd06fe7aa132138ec4d1bd14a86ba84

absl/container/internal/raw_hash_set.h

@@ -172,22 +172,6 @@
 #ifndef ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_
 #define ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_
 
-#ifdef __SSE2__
-#include <emmintrin.h>
-#endif
-
-#ifdef __SSSE3__
-#include <tmmintrin.h>
-#endif
-
-#ifdef _MSC_VER
-#include <intrin.h>
-#endif
-
-#ifdef __ARM_NEON
-#include <arm_neon.h>
-#endif
-
 #include <algorithm>
 #include <cmath>
 #include <cstdint>
@@ -215,6 +199,22 @@
 #include "absl/numeric/bits.h"
 #include "absl/utility/utility.h"
 
+#ifdef ABSL_INTERNAL_HAVE_SSE2
+#include <emmintrin.h>
+#endif
+
+#ifdef ABSL_INTERNAL_HAVE_SSSE3
+#include <tmmintrin.h>
+#endif
+
+#ifdef _MSC_VER
+#include <intrin.h>
+#endif
+
+#ifdef ABSL_INTERNAL_HAVE_ARM_NEON
+#include <arm_neon.h>
+#endif
+
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace container_internal {