tools: Build autoconf if needed and use it to patch libstdc++

tools/setup-autoconf.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+set -e
+source $(dirname $0)/setup-env.sh
+
+cd $LUNA_ROOT
+
+# libstdc++ needs autoconf (precisely version 2.69) so if the user has an older/more recent version, we must build autoconf from source.
+
+export AUTOCONF_VERSION=2.69
+
+mkdir -p toolchain/tarballs
+mkdir -p toolchain/build
+
+if [ ! -f toolchain/tarballs/autoconf-$AUTOCONF_VERSION.tar.gz ]; then
+    echo Downloading autoconf (precisely version 2.69)...
+
+    wget -Otoolchain/tarballs/autoconf-$AUTOCONF_VERSION.tar.gz https://ftp.gnu.org/gnu/autoconf/autoconf-$AUTOCONF_VERSION.tar.gz
+fi
+
+rm -rf toolchain/build/build-autoconf
+rm -rf toolchain/build/autoconf-$AUTOCONF_VERSION
+
+echo Extracting autoconf (precisely version 2.69)...
+
+tar xf toolchain/tarballs/autoconf-$AUTOCONF_VERSION.tar.xz -C toolchain/build/
+
+mkdir -p toolchain/build/build-autoconf
+
+cd toolchain/build/build-autoconf
+
+unset CC
+unset CXX
+unset LD
+unset AR
+
+echo Building autoconf (precisely version 2.69)...
+
+../autoconf-$AUTOCONF_VERSION/configure --prefix="/"
+make
+DESTDIR=$LUNA_ROOT/toolchain/dist make install

tools/setup-gcc.sh

@@ -36,6 +36,10 @@ patch -u -i $LUNA_ROOT/tools/gcc.patch -p 1 -d build
 
 cd -
 
+cd toolchain/build/gcc-$LUNA_GCC_VERSION_REQUIRED/libstdc++-v3
+autoconf
+cd -
+
 echo Configuring GCC...
 
 mkdir -p toolchain/build/gcc-$LUNA_ARCH

tools/setup.sh

@@ -1,6 +1,12 @@
 #!/usr/bin/env bash
 set -e
 
+if ! $(dirname $0)/test-autoconf.sh
+then
+    echo Building autoconf...
+    $(dirname $0)/setup-autoconf.sh
+fi
+
 if ! $(dirname $0)/test-binutils.sh
 then
     echo Building Binutils...

tools/test-autoconf.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+set -e
+source $(dirname $0)/setup-env.sh
+
+if [ -x "$(command -v autoconf)" ]
+then
+    if [ "$(autoconf --version | head -n 1 | awk '{ print $4 }')" == "2.69" ]
+    then
+        exit 0
+    else
+        echo "You have autoconf installed, but it is not version 2.69, which is required by libstdc++. Thus, we must build autoconf from source."
+        exit 1
+    fi
+else
+exit 1
+fi