[gnome-continuous-yocto/gnomeostree-3.28-rocko: 1762/8267] world-broken: Add libunwind for musl/arm

[Emmanuele Bassi <ebassi src gnome org>]

commit 309a6e01e3b40022c23df1f72ad5a6e9df65b334
Author: Khem Raj <raj khem gmail com>
Date:   Sun Aug 7 23:47:58 2016 -0700

    world-broken: Add libunwind for musl/arm
    
    gcc and libunwind race and when libunwind wins
    results are build fails for gcc as described
    this is only seen on musl/arm since on musl
    /usr/include is search before gcc fixed headers
    and unwind.h is in fixed headers. So it works
    ok on glibc but not on musl due to reversed search
    order.
    
    (From OE-Core rev: 2e9a88a21d21f2f71769899888fbbc994bc708f0)
    
    Signed-off-by: Khem Raj <raj khem gmail com>
    Signed-off-by: Ross Burton <ross burton intel com>
    Signed-off-by: Richard Purdie <richard purdie linuxfoundation org>

 meta/conf/distro/include/world-broken.inc |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/meta/conf/distro/include/world-broken.inc b/meta/conf/distro/include/world-broken.inc
index a5f6371..d4bdddf 100644
--- a/meta/conf/distro/include/world-broken.inc
+++ b/meta/conf/distro/include/world-broken.inc
@@ -47,3 +47,10 @@ EXCLUDE_FROM_WORLD_pn-perf_libc-musl = "1"
 
 # error: 'RTLD_NEXT' was not declared in this scope
 EXCLUDE_FROM_WORLD_pn-gcc-sanitizers_libc-musl = "1"
+
+# gcc fails to build when libuwind is staged before building gcc since
+# it then finds the unwind.h header from libunwind and not from libgcc
+# and on arm specially they are different since libgcc defines some functions
+# as macros which are functions in libunwind and it fails during linking
+# libbacktrace/backtrace.c:76: undefined reference to `_Unwind_GetIP'
+EXCLUDE_FROM_WORLD_pn-libunwind_libc-musl_arm = "1"