librustc: add LLVM LDFLAGS to deps

This commit let librustc automatically pickup LDFLAGS dependencies
inherited from LLVM, which may otherwise result in undefined
references to external symbols under certain linking environment.

A symptom of this issue is eg. a failure when trying to link against
librustc (due to unresolved ffi_*i symbols), while using a system-wide
LLVM.

Signed-off-by: Luca Bruno <lucab@debian.org>
travis: remove manually added RUSTFLAGS

Indirect dependencies should now be picked up through the
autogenerated llvmdeps.rs instead.

Signed-off-by: Luca Bruno <lucab@debian.org>
auto merge of #12651 : lucab/rust/llvmdep-ldflags, r=alexcrichton

This commit let librustc automatically pickup LDFLAGS dependencies
inherited from LLVM, which may otherwise result in undefined
references to external symbols under certain linking environment.

A symptom of this issue is eg. a failure when trying to link against
librustc (due to unresolved ffi_* symbols), while using a system-wide
LLVM.

Signed-off-by: Luca Bruno <lucab@debian.org>
Add /etc/terminfo to the terminfo search paths
auto merge of #12656 : Armavica/rust/terminfo, r=sfackler

According to `/etc/terminfo/README`,
```
This directory is for system-local terminfo descriptions. By default,
ncurses will search ${HOME}/.terminfo first, then /etc/terminfo (this
directory), then /lib/terminfo, and last not least /usr/share/terminfo.
```
Expand string literals and exprs inside of macros

A couple of syntax extensions manually expanded expressions, but it
wasn't done universally, most noticably inside of asm!().

There's also a bit of random cleanup.
test: Ignore some phase(syntax) tests

These tests are failing on the snap builders, and are now tagged with a FIXME.

cc #12102
auto merge of #12658 : sfackler/rust/asm-expand, r=alexcrichton

A couple of syntax extensions manually expanded expressions, but it
wasn't done universally, most noticably inside of asm!().

There's also a bit of random cleanup.
auto merge of #12659 : alexcrichton/rust/fix-snap, r=sfackler

These tests are failing on the snap builders, and are now tagged with a FIXME.

cc #12102