Refactoring build system for more control of inputs

scripts/templates/target.boot.j2

@@ -0,0 +1,35 @@
+{% extends "target.default.j2" %}
+
+{% block binaries %}
+ld = ld
+cc = clang
+cxx = clang++
+nasm = nasm
+{% endblock %}
+
+{% block variables %}
+
+ccflags = $ccflags $
+    -ggdb $
+    -nostdlib $
+    -ffreestanding $
+    -nodefaultlibs $
+    -fno-builtin $
+    -mno-sse $
+    -fno-omit-frame-pointer $
+    -mno-red-zone $
+    -fshort-wchar
+
+cxxflags = $cxxflags $
+    -nostdlibinc $
+    -fno-exceptions $
+    -fno-rtti
+
+ldflags = $ldflags $
+    -g $
+    -nostdlib $
+    -znocombreloc $
+	-Bsymbolic $
+    -nostartfiles
+
+{% endblock %}