libgcc.a is not mentioned in build-gpc.command. I guessed:
# setenv GPC_MAKE_FLAGS 'CC="gcc -arch i386"' # TDS: setenv GPC_MAKE_FLAGS 'CC="gcc -arch i386 -gdwarf-2"'
but it failed as above.
Also just guessing;
try instead adding --with-dwarf2 to
setenv GPC_CONFIG_EXTRAS "--with-arch=pentium-m --with-tune=prescott"
ie
setenv GPC_CONFIG_EXTRAS "--with-arch=pentium-m --with-tune=prescott --with-dwarf2"