app_conference.so : $(OBJS)
ifeq (${OSARCH},Darwin)
	$(CC) -pg -Xlinker -x -o $@ $(OBJS)

yields ...

gcc -pg -Xlinker -x -o app_conference.so app_conference.o conference.o member.o frame.o cli.o libspeex/preprocess.o libspeex/misc.o libspeex/smallft.o
/usr/bin/ld: Undefined symbols:
_main
_ast_log
_ast_register_application
_ast_softhangup
_ast_unregister_application
_ast_update_use_count
___use_ast_pthread_create_instead__
_ast_frdup
_ast_frfree
_ast_frisolate
_ast_translate
_ast_translator_build_path
_ast_translator_free_path
___ast_smoother_feed
_ast_answer
_ast_closestream
_ast_read
_ast_readframe
_ast_set_read_format
_ast_set_write_format
_ast_smoother_free
_ast_smoother_new
_ast_smoother_read
_ast_waitfor
_ast_write
_manager_event
_ast_cli
_ast_cli_register
_ast_cli_unregister
_ast_copy_string
_ast_openstream
collect2: ld returned 1 exit status
make: *** [app_conference.so] Error 1

========================================

app_conference.so : $(OBJS)
ifeq (${OSARCH},Darwin)
	$(CC) -pg -x -o $@ $(OBJS)

yields ...

gcc -pipe -Wall -Wmissing-prototypes -Wmissing-declarations -g  -I/Users/benjamin/asterisk-1.0.10/include/asterisk  -D_REENTRANT -D_GNU_SOURCE -O3 -ffast-math -funroll-all-loops -fprefetch-loop-arrays -fsingle-precision-constant -mcpu=7450 -faltivec -mabi=altivec -mdynamic-no-pic  -DCRYPTO -DAPP_CONFERENCE_DEBUG -Ilibspeex -DSILDET=2   -c -o libspeex/smallft.o libspeex/smallft.c
gcc -pg -x -o app_conference.so app_conference.o conference.o member.o frame.o cli.o libspeex/preprocess.o libspeex/misc.o libspeex/smallft.o
powerpc-apple-darwin8-gcc-4.0.0: app_conference.so: No such file or directory
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
powerpc-apple-darwin8-gcc-4.0.0: language -o not recognized
make: *** [app_conference.so] Error 1