"incompatible implicit declaration" warnings with GCC 4.2.1

[Juanma Barranquero]

  C:\emacs> gcc --version
  gcc (GCC) 4.2.1-sjlj (mingw32-2)
  Copyright (C) 2007 Free Software Foundation, Inc.

Compilation produces these warnings. They don't happen with gcc 3.4.5 (MinGW):

  gcc -I. -DWIN32_LEAN_AND_MEAN -D_WIN32_WINNT=0x0400 -D_X86_=1 -c
-gstabs+ -g3 -mno-cygwin -mtune=pentium4 -O2  -Di386 -D_CRTAPI1=_cdecl
-Demacs=1 -DWINDOWSNT -DDOS_NT -DHAVE_CONFIG_H -I../nt/inc -D_UCHAR_T
-DHAVE_NTGUI=1 -DUSE_CRT_DLL=1 -DPURESIZE=5000000 -o
oo-spd/i386/w32fns.o w32fns.c
  w32fns.c: In function 'gamma_correct':
  w32fns.c:1241: warning: incompatible implicit declaration of
built-in function 'pow'
  w32fns.c: In function 'w32_abort':
  w32fns.c:9127: warning: incompatible implicit declaration of
built-in function 'abort'

             Juanma