Fix std::getopts::opts_present() to check value.

Currently the opts_present() function only checks to see if the option is
configured in the match, but doesn't actually check to see if the option
value has been set.  This means that opt_present('h') may return false while
opts_present([~'h']) returns true.

Add a test case to catch this condition and fix opts_present() to check
the value before returning true.

Note, there is another API difference between these two functions that this
does not address.  Currently if you pass a non-configured option to
opt_present() the program will fail!(), but opts_present() simply returns
false.  If it is acceptable to standardize on the fail!() then opts_present()
should probably be implemented in terms of the opt_present() function.
Avoid propagating link_arg values that are unlikely to be resolveable under arbitrary directories.
Parse inline assembly.
Wrap llvm::InlineAsm::AsmDialect
Require unsafe block for inline assembly.
Create asm! syntax extension.
Stop parsing __asm__.
Parse operands properly and add a way to indicate volatile asm.
Keep everything tidy.
Add alignstack option for inline asm.
auto merge of #5317 : luqmana/rust/inline-asm, r=graydon

```Rust
#[cfg(target_os = "macos")]
fn helloworld() {
    unsafe {
        asm!(".pushsection __RODATA, __rodata
                  msg: .asciz \"Hello World!\"
              .popsection
              movq msg@GOTPCREL(%rip), %rdi
              call _puts");
    }
}

#[cfg(target_os = "linux")]
fn helloworld() {
    unsafe {
        asm!(".pushsection .rodata
                  msg: .asciz \"Hello World!\"
              .popsection
              movq msg@GOTPCREL(%rip), %rdi
              call puts");
    }
}

fn main() {
    helloworld();
}
```

```
% rustc foo.rs
% ./foo
Hello World!
```
auto merge of #5329 : wanderview/rust/std-getopts-opts_present, r=graydon

Currently the opts_present() function only checks to see if the option is
configured in the match, but doesn't actually check to see if the option
value has been set.  This means that opt_present('h') may return false while
opts_present([~'h']) returns true.

Add a test case to catch this condition and fix opts_present() to check
the value before returning true.

Note, there is another API difference between these two functions that this
does not address.  Currently if you pass a non-configured option to
opt_present() the program will fail!(), but opts_present() simply returns
false.  If it is acceptable to standardize on the fail!() then opts_present()
should probably be implemented in terms of the opt_present() function.
syntax: implement #[deriving] meta-attribute
auto merge of #5320 : apasel422/rust/metaderive, r=graydon

This is the first in a series of patches I'm working on to clean up the code related to `deriving`. This patch allows

```
#[deriving_eq]
#[deriving_iter_bytes]
#[deriving_clone]
struct Foo { bar: uint }
```
to be replaced with:
```
#[deriving(Eq, IterBytes, Clone)]
struct Foo { bar: uint }
```
It leaves the old attributes alone for the time being.

Eventually I'd like to incorporate the new closest-match-suggestion infrastructure for mistyped trait names, and also pass the sub-attributes to the deriving code, so that the following will be possible:
```
#[deriving(TotalOrd(qux, bar))]
struct Foo { bar: uint, baz: char, qux: int }
```
This says to derive an `impl` in which the objects' `qux` fields are compared first, followed by `bar`, while `baz` is ignored in the comparison. If no fields are specified explicitly, all fields will be compared in the order they're defined in the `struct`. This might also be useful for `Eq`. Coming soon.
auto merge of #5332 : jdm/rust/transitivelink, r=graydon

The original change bit Servo because rust-harfbuzz includes libharfbuzz.a in its link_args. This works fine in the rust-harfbuzz subdirectory where the static library resides, but when this is propagated to servo_gfx, the lirbrary can no longer be found since it's a relative path.
core: Turn off rtdebug logging
libcore: Attempt to put out burning tree on Mac by using the old symbol on 32 bit. rs=bustage
Work around linkage bug cross-compiling from x86_64-apple-darwin to i686-apple-darwin

The correct opendir/readdir to use appear to be the 64-bit versions called
opendir$INODE64, etc. but for some reason I can't get them to link properly
on i686. Putting them in librustrt and making gcc figure it out works.
This mystery will have to wait for another day.