[gnutls-help] Failure building v3.3.18 on MinGW: undefned reference to rpl_fseek

[Test User]

make[4]: Entering directory `/c/data/open_source/gnutls-3.3.18-build/lib'
  CC       system.lo
  CCLD     libgnutls.la
opencdk/.libs/libminiopencdk.a(armor.o): In function `armor_decode':
c:\data\open_source\gnutls-3.3.18-build\lib\opencdk/../../../gnutls-3.3.18/lib/o
pencdk/armor.c:232: undefined reference to `rpl_fseek'
opencdk/.libs/libminiopencdk.a(stream.o): In function `cdk_stream_seek':
c:\data\open_source\gnutls-3.3.18-build\lib\opencdk/../../../gnutls-3.3.18/lib/o
pencdk/stream.c:1081: undefined reference to `rpl_fseek'
collect2.exe: error: ld returned 1 exit status

I understand that the system is trying to replace fseek with rpl_fseek,
but where is the definition of rpl_fseek?