Fix some more FreeBSD4 issues (based on a patch from grarpamp)

Apparently, freebsd 4 doesn't like malloc.h, needs sys/param.h for
MIN/MAX, and doesn't have a SIZE_MAX.

For bug 3894.

changes/bug3894_more

+  o Build fixes:
+    - Clean up some code issues that prevented Tor from building on older
+      BSDs.  Fixes bug 3894; reported by grarpamp.
+      

configure.in

@@ -417,6 +417,8 @@ dnl These headers are not essential
 
 AC_CHECK_HEADERS(stdint.h sys/types.h inttypes.h sys/param.h sys/wait.h limits.h sys/limits.h netinet/in.h arpa/inet.h machine/limits.h syslog.h sys/time.h sys/resource.h inttypes.h utime.h sys/utime.h sys/mman.h netinet/in6.h malloc.h sys/syslimits.h malloc/malloc.h linux/types.h sys/file.h malloc_np.h sys/prctl.h)
 
+AC_CHECK_HEADERS(sys/param.h)
+
 TOR_CHECK_PROTOTYPE(malloc_good_size, HAVE_MALLOC_GOOD_SIZE_PROTOTYPE,
 [#ifdef HAVE_MALLOC_H
 #include <malloc.h>

src/common/compat.h

@@ -19,6 +19,9 @@
 #include <ws2tcpip.h>
 #endif
 #endif
+#ifdef HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif

src/common/torint.h

@@ -182,6 +182,16 @@ typedef unsigned __int64 uint64_t;
 #endif
 #endif
 
+#ifndef SIZE_MAX
+#if SIZEOF_SIZE_T == 8
+#define SIZE_MAX UINT64_MAX
+#elif  SIZEOF_SIZE_T == 4
+#define SIZE_MAX UINT32_MAX
+#else
+#error "Can't define SIZE_MAX"
+#endif
+#endif
+
 #ifndef HAVE_SSIZE_T
 #if SIZEOF_SIZE_T == 8
 typedef int64_t ssize_t;

src/common/util.c

@@ -77,7 +77,7 @@
 #include <malloc/malloc.h>
 #endif
 #ifdef HAVE_MALLOC_H
-#ifndef OPENBSD
+#if !defined(OPENBSD) && !defined(__FreeBSD__)
 /* OpenBSD has a malloc.h, but for our purposes, it only exists in order to
  * scold us for being so stupid as to autodetect its presence.  To be fair,
  * they've done this since 1996, when autoconf was only 5 years old. */