Change check for rpc/xdr.h

Change from checking if the file exists to if the symbol xdrstdio_create exists. Should fix #1996

CMakeLists.txt

@@ -216,15 +216,15 @@ check_include_file(conio.h      HAVE_CONIO_H)
 check_include_file(sys/time.h   HAVE_SYS_TIME_H)
 check_include_file(time.h       HAVE_TIME_H)
 check_include_file(strings.h    HAVE_STRINGS_H)
-check_include_file(rpc/xdr.h    HAVE_RPC_XDR_H)
 check_include_file(regex.h      HAVE_REGEX_H)
 check_include_file_cxx(sstream  HAVE_SSTREAM)
 
-check_symbol_exists(rint          "math.h"     HAVE_RINT)
-check_symbol_exists(snprintf      "stdio.h"    HAVE_SNPRINTF)
-check_symbol_exists(sranddev      "stdlib.h"   HAVE_SRANDDEV)
-check_symbol_exists(strcasecmp    "string.h"   HAVE_STRCASECMP)
-check_symbol_exists(strncasecmp   "string.h"   HAVE_STRNCASECMP)
+check_symbol_exists(rint             "math.h"     HAVE_RINT)
+check_symbol_exists(snprintf         "stdio.h"    HAVE_SNPRINTF)
+check_symbol_exists(sranddev         "stdlib.h"   HAVE_SRANDDEV)
+check_symbol_exists(strcasecmp       "string.h"   HAVE_STRCASECMP)
+check_symbol_exists(strncasecmp      "string.h"   HAVE_STRNCASECMP)
+check_symbol_exists(xdrstdio_create  "rpc/xdr.h"  HAVE_RPC_XDR_H)
 
 # BSDs don't link against libdl, but rather libc
 check_library_exists(dl dlopen "" HAVE_LIBDL)