Moved stdlib to a seperate folder and added some more headers that are required for compiling libgcc (no implementation yet).

targets/_any/stdlib/SConscript

@@ -0,0 +1,13 @@
+
+Import('env')
+
+stdlib_sources = Split('''
+    src/assert.cpp
+    src/stdio.cpp
+    src/stdlib.cpp
+    src/string.cpp
+''')
+
+env.Append(KERNEL_SOURCES = [env.File(f) for f in stdlib_sources])
+
+Return('env')