Taking a chance here. Under both Solaris and FreeBSD, there is a

/usr/include/limits.h (which quiets the costsize.c warnings)...under
FreeBSD, /usr/include/limits.h *includes* machine/limits.h, while under
Solaris, there is no such things as /usr/include/machine...

Problem with Solaris pointed out by Mark Wahl

src/backend/optimizer/path/costsize.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.9 1997/01/13 03:54:15 bryanh Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.10 1997/01/22 04:41:45 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -22,7 +22,7 @@
 # define MAXINT        INT_MAX
 #else
 # if defined(USE_LIMITS_H)
-#  include <machine/limits.h>
+#  include <limits.h>
 #  define MAXINT	INT_MAX
 # else
 #  ifdef USE_VALUES_H

src/include/config.h

@@ -98,6 +98,7 @@
 #endif
 
 #if defined(i386_solaris) 
+#  define USE_LIMITS_H
 #  define USE_POSIX_TIME 
 #  define USE_POSIX_SIGNALS
 #  define NEED_ISINF 
@@ -172,6 +173,7 @@
 #endif
 
 #if defined(sparc_solaris)
+#  define USE_LIMITS_H
 #  define USE_POSIX_TIME 
 #  define USE_POSIX_SIGNALS
 #  define NEED_ISINF