bdwgc: Check for getcontext() API during configure

This helps in compiling dependent components like
guile where it shows the problem of missing getcontext
API when using libc which dont implement it e.g. musl

(From OE-Core rev: ee60d562c7352fb5a595274490e7f377645aa650)

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/recipes-support/bdwgc/bdwgc/0001-configure.ac-add-check-for-NO_GETCONTEXT-definition.patch

@@ -0,0 +1,29 @@
+configure.ac: add check for NO_GETCONTEXT definition
+
+Signed-off-by: Samuel Martin <s.martin49@gmail.com>
+[yann.morin.1998@free.fr: add a comment, change variable name, use
+ AS_IF, remove debug traces, use AC_CHECK_FUNCS (as suggested by
+ Thomas)]
+Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
+Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+
+---
+Upstream-Status: Pending
+ configure.ac | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+--- bdwgc-7.2f.orig/configure.ac	2014-06-01 19:00:47.000000000 +0200
++++ bdwgc-7.2f/configure.ac	2014-12-23 14:13:11.585716713 +0100
+@@ -365,6 +365,12 @@
+   AC_MSG_RESULT($ac_cv_fno_strict_aliasing)
+ fi
+ 
++# Check for getcontext (uClibc can be configured without it, for example)
++AC_CHECK_FUNCS([getcontext])
++AS_IF([test "$ac_cv_func_getcontext" = "no"],
++  [CFLAGS="$CFLAGS -DNO_GETCONTEXT"
++   CPPFLAGS="$CPPFLAGS -DNO_GETCONTEXT"])
++
+ case "$host" in
+ # While IRIX 6 has libdl for the O32 and N32 ABIs, it's missing for N64
+ # and unnecessary everywhere.

meta/recipes-support/bdwgc/bdwgc_7.4.2.bb

@@ -23,6 +23,7 @@ LIC_FILES_CHKSUM = "file://README.QUICK;md5=55f5088f90a982fed7af9a4897047ef7"
 
 SRC_URI = "http://www.hboehm.info/gc/gc_source/gc-${PV}.tar.gz \
            file://0001-fix-build-with-musl.patch \
+           file://0001-configure.ac-add-check-for-NO_GETCONTEXT-definition.patch \
           "
 
 SRC_URI[md5sum] = "12c05fd2811d989341d8c6d81f66af87"