Bring back implicit usage of built-in functions of the standard library

.github/workflows/build.yml

@@ -79,6 +79,10 @@ jobs:
     - uses: actions/checkout@main
       with:
         submodules: true
+    - name: Setup Python
+      uses: actions/setup-python@main
+      with:
+        python-version: '3.12'
     - name: Restore from cache
       uses: actions/cache@main
       with:

build.sh

@@ -207,6 +207,32 @@ for target in "${targets[@]}"; do
 		patch --directory="${toolchain_directory}/${triple}" --strip='1' --input="${workdir}/patches/linux_pim.patch"
 	fi
 
+	cd "${toolchain_directory}/${triple}/include"
+
+	if ! (( is_native )); then
+		CC="${triple}-gcc" python "${workdir}/tools/make_builtins.py"
+
+		if [ -f './builtin_ctype.h' ]; then
+			echo '#include <builtin_ctype.h>' >> './ctype.h'
+		fi
+
+		if [ -f './builtin_math.h' ]; then
+			echo '#include <builtin_math.h>' >> './math.h'
+		fi
+
+		if [ -f './builtin_stdio.h' ]; then
+			echo '#include <builtin_stdio.h>' >> './stdio.h'
+		fi
+
+		if [ -f './builtin_complex.h' ]; then
+			echo '#include <builtin_complex.h>' >> './complex.h'
+		fi
+
+		if [ -f './builtin_stdlib.h' ]; then
+			echo '#include <builtin_stdlib.h>' >> './stdlib.h'
+		fi
+	fi
+
 	[ -d "${binutils_directory}/build" ] || mkdir "${binutils_directory}/build"
 
 	cd "${binutils_directory}/build"