Add support for NetBSD.

src/m/amdx86-64.h

@@ -125,12 +125,16 @@ Boston, MA 02110-1301, USA.  */
 #undef LIB_STANDARD
 #define LIB_STANDARD -lgcc -lc -lgcc /usr/lib/crtend.o
 
+#elif defined(__NetBSD__)
+
+/* LIB_STANDARD and START_FILES set correctly in s/netbsd.h */
+
 #elif defined(sun)
 
 #undef START_FILES
 #undef LIB_STANDARD
 
-#else /* !__OpenBSD__ && !__FreeBSD__ && !sun */
+#else /* !__OpenBSD__ && !__FreeBSD__ && !__NetBSD__ && !sun */
 
 #undef START_FILES
 #ifdef HAVE_X86_64_LIB64_DIR

src/m/hp800.h

@@ -174,6 +174,14 @@ Boston, MA 02110-1301, USA.  */
 #define rindex strrchr
 
 #endif /* __hpux */
+
+/* Systems with GCC don't need to lose. */
+#ifdef __NetBSD__
+# ifdef __GNUC__
+#  define alloca __builtin_alloca
+#  define HAVE_ALLOCA
+# endif /* __GNUC__ */
+#endif /* __NetBSD__ */
 
 /* arch-tag: 809436e6-1645-4b92-b40d-2de5d6e7227c
    (do not change this comment) */