cc: add options to differentiate the need for pass-1 and pass-2

In some cases, building the core pass-1 is unneeded, as the C library
will not try to build anything when installing headers, or sill not
install anything at all.

This is for example the case for newlib, wihch does not require a core
pass-1 since it builds nothing and installs no header.

This should also be the case for newer glibc-es with newer gcc-es,
which no longer require a core pass-1, since the circular dependency
glibc <-> gcc (about TLS?) has been resolved.

Reported-by: Trevor Woerner <trevor.woerner@linaro.org>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

This patch is courtesy of OpenEmbedded, by Khem Raj <raj.khem@gmail.com>

http://cgit.openembedded.org/cgit.cgi/openembedded/commit/?id=b85b779688f0abc389e3c25d06b54de8b86385c1

Index: ltrace-0.5.3/Makefile.in

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

--- ltrace-0.5.3.orig/Makefile.in	2009-10-23 22:06:08.130304691 -0700

+++ ltrace-0.5.3/Makefile.in	2009-10-23 22:06:53.160369614 -0700

@@ -39,6 +39,8 @@ ltrace:		main.o libltrace.a

 libltrace.a: 	sysdeps/sysdep.o $(OBJ)

 		$(AR) rcv $@ $^

+$(OBJ):		sysdeps/sysdep.o

+

 sysdeps/sysdep.o: dummy

 		$(MAKE) -C sysdeps/$(OS)