gcc: Allow using libc++

With the addition of the C++ runtime setting added recently, allow
gcc to use libc++ as its runtime. There's some minor fixes still
required, such as allowing setting the unwinder library. But this
allows for testing libc++ with gcc.

(From OE-Core rev: f84ae97e2bc081c972e78ee4a958f21111dbbfb6)

Signed-off-by: Daniel McGregor <daniel.mcgregor@vecima.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/gcc/gcc-14.1.inc

@@ -108,10 +108,4 @@ EXTRA_OECONF_INITIAL = "\
     --disable-libssp \
 "
 
-EXTRA_OECONF_PATHS = "\
-    --with-gxx-include-dir=/not/exist{target_includedir}/c++/${BINV} \
-    --with-sysroot=/not/exist \
-    --with-build-sysroot=${STAGING_DIR_TARGET} \
-"
-
 CVE_STATUS[CVE-2021-37322] = "cpe-incorrect: Is a binutils 2.26 issue, not gcc"

meta/recipes-devtools/gcc/gcc-cross-canadian.inc

@@ -12,6 +12,7 @@ require gcc-configure-common.inc
 EXTRA_OECONF += "--with-plugin-ld=ld"
 EXTRA_OECONF_PATHS = "\
     --with-gxx-include-dir=/not/exist${target_includedir}/c++/${BINV} \
+    --with-gxx-libcxx-include-dir=/not/exist${target_includedir}/c++/v1 \
     --with-build-time-tools=${STAGING_DIR_NATIVE}${prefix_native}/${TARGET_SYS}/bin \
     --with-sysroot=/not/exist \
     --with-build-sysroot=${STAGING_DIR_TARGET} \

meta/recipes-devtools/gcc/gcc-cross.inc

@@ -37,6 +37,7 @@ EXTRA_OECONF:remove:libc-newlib = "--enable-threads=posix"
 
 EXTRA_OECONF_PATHS = "\
     --with-gxx-include-dir=/not/exist${target_includedir}/c++/${BINV} \
+    --with-gxx-libcxx-include-dir=/not/exist${target_includedir}/c++/v1 \
     --with-sysroot=/not/exist \
     --with-build-sysroot=${STAGING_DIR_TARGET} \
 "

meta/recipes-devtools/gcc/gcc-target.inc

@@ -2,6 +2,7 @@ GCCMULTILIB = "--enable-multilib"
 require gcc-configure-common.inc
 
 EXTRA_OECONF_PATHS = "\
+    --with-gxx-libcxx-include-dir=${target_includedir}/c++/v1 \
     --with-build-sysroot=${STAGING_DIR_TARGET} \
 "