Fix up the build scripts

[mstewartgallus]

Now the modules are isolated and everything installs properly.

Bad build scripts make me really, really angry so I made everything much cleaner.

[xiw]

awesome! thanks!

sorry i don't have a testing machine this week. does make check work (without make install)?

also im not particular into hierarchical source directory---with this patch we would have to repeat *_CXXFLAGS several times rather than keeping them in one place.

[mstewartgallus]

I tried fixing the test suite but I have an old version of Ruby so I can't fully test the test suite.
In the meanwhile I'll work on using Automake's %C% and %D% substitutions so I can just include makefiles instead of using SUBDIRS so that a global CXXFLAGS works.

[denji]

Flag CPP incorrect work, please remove.
configure: error: C preprocessor fails sanity check

unset ENV[CPP], work.

llvm-config tools automatically configure LLVM environment.

usage: llvm-config <OPTION>... [<COMPONENT>...]
Get various configuration information needed to compile programs which use
LLVM. Typically called from 'configure' scripts. Examples:
llvm-config --cxxflags
llvm-config --ldflags
llvm-config --libs engine bcreader scalaropts
Options:
--version Print LLVM version.
--prefix Print the installation prefix.
--src-root Print the source root LLVM was built from.
--obj-root Print the object root used to build LLVM.
--bindir Directory containing LLVM executables.
--includedir Directory containing LLVM headers.
--libdir Directory containing LLVM libraries.
--cppflags C preprocessor flags for files that include LLVM headers.
--cflags C compiler flags for files that include LLVM headers.
--cxxflags C++ compiler flags for files that include LLVM headers.
--ldflags Print Linker flags.
--system-libs System Libraries needed to link against LLVM components.
--libs Libraries needed to link against LLVM components.
--libnames Bare library names for in-tree builds.
--libfiles Fully qualified library filenames for makefile depends.
--components List of all possible components.
--targets-built List of all targets currently built.
--host-target Target triple used to configure LLVM.
--build-mode Print build mode of LLVM tree (e.g. Debug or Release).
--assertion-mode Print assertion mode of LLVM tree (ON or OFF).
Typical components:
all All LLVM libraries (default).
engine Either a native JIT or a bitcode interpreter.