chromium: Set LIBCPLUSPLUS to use libc++

This should fix issue seen with
#551

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

Author: kraj

meta-chromium/recipes-browser/chromium/chromium.inc

@@ -24,6 +24,20 @@ TOOLCHAIN:class-native = "clang"
 # https://github.com/kraj/meta-clang/issues/449).
 RUNTIME = "llvm"
 
+# meta-clang uses RUNTIME variable to add build dependencies on libcxx/compiler-rt
+# but does not add compiler options to commandline. It expects compiler's own
+# defaults to be used and compiler's buildtime defaults are chosen based on
+# global RUNTIME variable setting when building clang compiler, which defaults to 'gnu'.
+# For chromium libc++ is expected to be used therefore ensure that
+# right build flags are set for chromium irrespective of
+# distro defaults (which could be 'gnu' or 'llvm').
+# This also ensures that it does not rely too much on meta-clang's defaults.
+LIBCPLUSPLUS = "-stdlib=libc++"
+
+# LIBCPLUSPLUS is included in CXXFLAGS and LDFLAGS, but chromium doesn't respect it
+# add it to TUNE_CCARGS as well to include it in CC/CXX variables which are respected.
+TUNE_CCARGS += "${LIBCPLUSPLUS}"
+
 inherit mime-xdg pythonnative
 DEPENDS += "python-setuptools-native"