Encontrado el fallo del de cabecera es pic1687x.h
Ahora me sale esto
C:\Program Files (x86)\HI-TECH Software\PICC>picc --chip=16f876 c:\compilacion\modmpg.c
(1273) Omniscient Code Generation not available in Lite mode (warning)
HI-TECH C Compiler for PIC10/12/16 MCUs (Lite Mode) V9.70
Copyright (C) 2009 Microchip Technology Inc.
C:\Program Files (x86)\HI-TECH Software\PICC\9.70\include\pic1687x.h:
3: #warning Header file pic1687x.h included directly. Use #include <htc.h> instead.
^ (162) #warning: Header file pic1687x.h included directly. Use #include
<htc.h> instead. (warning)
c:\compilacion\modmpg.c: MakeModBusFN03()
235: FSR = (&buffer) + 3;
^ (358) illegal conversion of pointer to integer (warning)
295: break;
^ (345) unreachable code (warning)
Memory Summary:
Program space used 447h ( 1095) of 2000h words ( 13.4%)
Data space used 70h ( 112) of 170h bytes ( 30.4%)
EEPROM space used 0h ( 0) of 100h bytes ( 0.0%)
Configuration bits used 0h ( 0) of 1h word ( 0.0%)
ID Location space used 0h ( 0) of 4h bytes ( 0.0%)
Running this compiler in PRO mode, with Omniscient Code Generation enabled,
produces code which is typically 40% smaller than in Lite mode.
The HI-TECH C PRO compiler output for this code could be 438 words smaller.
See
http://microchip.htsoft.com/portal/pic_pro for more information.