gcc-runtime_8.1.bb: disable ifuncs in libatomic for arm arch

This will solve the mcpu/march conflicts we get when -mcpu=cortex-a7
is passed on cmdline since it will become incompatible with default
ifuncs in libatomic which is using armv7-a

(From OE-Core rev: 015b0d8ed6aa766e8cc96d10218ac86a28728bf9)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/gcc/gcc-runtime_8.1.bb

@@ -1,6 +1,9 @@
 require recipes-devtools/gcc/gcc-${PV}.inc
 require gcc-runtime.inc
 
+# Disable ifuncs for libatomic on arm conflicts -march/-mcpu
+EXTRA_OECONF_append_arm = " libat_cv_have_ifunc=no "
+
 FILES_libgomp-dev += "\
     ${libdir}/gcc/${TARGET_SYS}/${BINV}/include/openacc.h \
 "