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>

     1.1 --- a/config/cc.in	Mon May 05 21:54:03 2014 +0200
     1.2 +++ b/config/cc.in	Mon May 05 23:29:48 2014 +0200
     1.3 @@ -9,7 +9,15 @@
     1.4      string
     1.5  
     1.6  config CC_CORE_PASSES_NEEDED
     1.7 -	bool
     1.8 +    bool
     1.9 +    select CC_CORE_PASS_1_NEEDED
    1.10 +    select CC_CORE_PASS_2_NEEDED
    1.11 +
    1.12 +config CC_CORE_PASS_1_NEEDED
    1.13 +    bool
    1.14 +
    1.15 +config CC_CORE_PASS_2_NEEDED
    1.16 +    bool
    1.17  
    1.18  source "config.gen/cc.in"
    1.19