configure: a skinny configuration script.
supported switches:
-------------------
--help
--prefix
--bindir
--libdir
--includedir
--syslibdir
--mandir
--libexecdir
--build
--host
--target
--arch
--toolchain
--sysroot
--cross-compile
--shell
--debug
supported variables:
--------------------
PREFIX
BINDIR
LIBDIR
INCLUDEDIR
LIBDIR
MANDIR
DOCDIR
LIBEXECDIR
CC
CPP
CXX
BUILD
HOST
TARGET
ARCH
TOOLCHAIN
SYSROOT
CROSS_COMPILE
SHELL
CFLAGS
CFLAGS_DEBUG
CFLAGS_COMMON
CFLAGS_CMDLINE
CFLAGS_CONFIG
CFLAGS_SYSROOT
CFLAGS_PATH
LDFLAGS
LDFLAGS_DEBUG
LDFLAGS_COMMON
LDFLAGS_CMDLINE
LDFLAGS_CONFIG
LDFLAGS_SYSROOT
LDFLAGS_PATH
PE_SUBSYSTEM
PE_IMAGE_BASE
PE_CONFIG_DEFS
ELF_EH_FRAME
ELF_HASH_STYLE
ELF_CONFIG_DEFS
NATIVE_CC
NATIVE_OS
NATIVE_OS_BITS
NATIVE_OS_UNDERSCORE