Use LLVM-style command line (instead of DMD-style)

Note: For a backward compatible interface, use the new bin/ldmd script. It
      supports all old options while passing on anything it doesn't recognize.

Some changes caused by this:
* -debug and -version are now -d-debug and -d-version due to a conflict with
  standard LLVM options.
* All "flag" options now allow an optional =true/=1/=false/=0 suffix.
* Some "hidden debug switches" starting with "--" were renamed because LLVM
  doesn't care about the number of dashes, so they were conflicting with other
  options (such as -c).
  The new versions start with "-hidden-debug-" instead of "--"
* --help works, but has a non-zero exit code. This breaks some Tango scripts
  which use it to test for compiler existence. See tango.patch.

Some changes not (directly) caused by this;
* (-enable/-disable)-FOO options are now available for pre- and postconditions.
* -march is used instead of -m (like other LLVM programs), but -m is an alias
  for it.
* -defaultlib, -debuglib, -d-debug and -d-version allow comma-separated values.
  The effect should be identical to specifying the same option multiple times.
  I decided against allowing these for some other options because paths might
  contain commas on some systems.
* -fPIC is removed in favor of the standard LLVM option -relocation-model=pic

Bug:
* If -run is specified as the last argument in DFLAGS, no error is generated.
  (Not very serious IMHO)

dmd/module.c

@@ -44,6 +44,19 @@
 #include "d-dmd-gcc.h"
 #endif
 
+
+#include "llvm/Support/CommandLine.h"
+
+static llvm::cl::opt<bool> preservePaths("op",
+    llvm::cl::desc("Do not strip paths from source file"),
+    llvm::cl::ZeroOrMore);
+
+static llvm::cl::opt<bool> fqnNames("oq",
+    llvm::cl::desc("Write object files with fully qualified names"),
+    llvm::cl::ZeroOrMore);
+
+
+
 ClassDeclaration *Module::moduleinfo;
 
 Module *Module::rootModule;
@@ -139,12 +152,12 @@ File* Module::buildFilePath(char* forcename, char* path, char* ext)
 	argobj = forcename;
     else
     {
-	if (global.params.preservePaths)
+	if (preservePaths)
 	    argobj = (char*)this->arg;
 	else
 	    argobj = FileName::name((char*)this->arg);
 
-	if (global.params.fqnNames)
+	if (fqnNames)
 	{
 	    if(md)
 		argobj = FileName::replaceName(argobj, md->toChars());