Fix build on Solaris 10 i386

Fix build on Solaris 10 i386

AC_SYS_LARGEFILE defines _FILE_OFFSET_BITS in src/config.h,
so we need this header first before including system headers.

Thanks to @dago for the report.

Fixes:
  CC       collectd-utils_random.o
In file included from collectd.h:31:0,
                 from utils_random.c:29:
../../src/config.h:1646:0: error: "_FILE_OFFSET_BITS" redefined
[-Werror]
 #define _FILE_OFFSET_BITS 64
 ^
In file included from
/opt/csw/lib/gcc/i386-pc-solaris2.10/5.2.0/include-fixed/pthread.h:20:0,
                 from utils_random.c:27:
/opt/csw/lib/gcc/i386-pc-solaris2.10/5.2.0/include-fixed/sys/feature_tests.h:196:0:
note: this is the location of the previous definition
 #define _FILE_OFFSET_BITS 32
 ^
cc1: all warnings being treated as errors

(cherry picked from commit a41f312a8d48a989dfba00a8b43532c60f67caba)