libcxx: Fix cflags and ldflags for using compiler runtime

-stdlib is needed in both cxxflags and ldflags since c++ compiler
will use these to chose the right c++ headers and libraries during link

-rtlib and -unwindlib are only needed during linking

Use LLVM_HOST_TRIPLE during cross compiling compiler-rt for target
this is used by cmake to compute target and compiler triples

Fix LLVM_RUNTIME_TARGETS to use HOST_ARCH, it does not need cross
compile triple which HOST_SYS is passing here

(From OE-Core rev: d1ae4087c548a78e90687b64764f621b070e3ec5)

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

meta/recipes-devtools/clang/libcxx_git.bb

@@ -51,8 +51,8 @@ CC = "${CCACHE}${HOST_PREFIX}clang ${HOST_CC_ARCH}${TOOLCHAIN_OPTIONS}"
 CXX = "${CCACHE}${HOST_PREFIX}clang++ ${HOST_CC_ARCH}${TOOLCHAIN_OPTIONS}"
 BUILD_CC = "${CCACHE}clang ${BUILD_CC_ARCH}"
 BUILD_CXX = "${CCACHE}clang++ ${BUILD_CC_ARCH}"
-CFLAGS += "${COMPILER_RT}"
-CXXFLAGS += "${COMPILER_RT} ${LIBCPLUSPLUS}"
+LDFLAGS += "${COMPILER_RT} ${UNWINDLIB} ${LIBCPLUSPLUS}"
+CXXFLAGS += "${LIBCPLUSPLUS}"
 
 OECMAKE_SOURCEPATH = "${S}/llvm"
 EXTRA_OECMAKE += "\
@@ -71,7 +71,7 @@ EXTRA_OECMAKE += "\
                   -DLIBCXX_CXX_ABI_LIBRARY_PATH=${B}/lib${LLVM_LIBDIR_SUFFIX} \
                   -S ${S}/runtimes \
                   -DLLVM_ENABLE_RUNTIMES='libcxx;libcxxabi;libunwind' \
-                  -DLLVM_RUNTIME_TARGETS=${HOST_SYS} \
+                  -DLLVM_RUNTIME_TARGETS=${HOST_ARCH} \
                   -DLLVM_LIBDIR_SUFFIX=${LLVM_LIBDIR_SUFFIX} \
                   -DLLVM_APPEND_VC_REV=OFF \
                   -DCMAKE_BUILD_WITH_INSTALL_RPATH=ON \
@@ -81,7 +81,7 @@ EXTRA_OECMAKE:append:class-target = " \
                   -DCMAKE_AR=${STAGING_BINDIR_TOOLCHAIN}/${AR} \
                   -DCMAKE_NM=${STAGING_BINDIR_TOOLCHAIN}/${NM} \
                   -DCMAKE_RANLIB=${STAGING_BINDIR_TOOLCHAIN}/${RANLIB} \
-                  -DLLVM_DEFAULT_TARGET_TRIPLE=${HOST_SYS} \
+                  -DLLVM_HOST_TRIPLE=${TARGET_SYS} \
                   -DCMAKE_POSITION_INDEPENDENT_CODE=ON \
 "