Merge branch 'dt/refs-check-refname-component-sse'

Further micro-optimization of a leaf-function.

* dt/refs-check-refname-component-sse:
  refs.c: SSE2 optimizations for check_refname_component

git-compat-util.h

@@ -685,6 +685,17 @@ void git_qsort(void *base, size_t nmemb, size_t size,
 #endif
 #endif
 
+#if defined(__GNUC__) && defined(__x86_64__)
+#include <emmintrin.h>
+/*
+ * This is the system memory page size; it's used so that we can read
+ * outside the bounds of an allocation without segfaulting.
+ */
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 4096
+#endif
+#endif
+
 #ifdef UNRELIABLE_FSTAT
 #define fstat_is_reliable() 0
 #else