Refine privacy error messages to be more accurate

This stops labeling everything as "is private" when in fact the destination may
be public. Instead, the clause "is inaccessible" is used and the private part of
the flag is called out with a "is private" message.

Closes #9793
Remove jemalloc from the runtime

As discovered in #9925, it turns out that we weren't using jemalloc on most
platforms. Additionally, on some platforms we were using it incorrectly and
mismatching the libc version of malloc with the jemalloc version of malloc.

Additionally, it's not clear that using jemalloc is indeed a large performance
win in particular situtations. This could be due to building jemalloc
incorrectly, or possibly due to using jemalloc incorrectly, but it is unclear at
this time.

Until jemalloc can be confirmed to integrate correctly on all platforms and has
verifiable large performance wins on platforms as well, it shouldn't be part of
the default build process. It should still be available for use via the
LD_PRELOAD trick on various architectures, but using it as the default allocator
for everything would require guaranteeing that it works in all situtations,
which it currently doesn't.

Closes #9925
auto merge of #9933 : alexcrichton/rust/no-jemalloc, r=brson

As discovered in #9925, it turns out that we weren't using jemalloc on most
platforms. Additionally, on some platforms we were using it incorrectly and
mismatching the libc version of malloc with the jemalloc version of malloc.

Additionally, it's not clear that using jemalloc is indeed a large performance
win in particular situtations. This could be due to building jemalloc
incorrectly, or possibly due to using jemalloc incorrectly, but it is unclear at
this time.

Until jemalloc can be confirmed to integrate correctly on all platforms and has
verifiable large performance wins on platforms as well, it shouldn't be part of
the default build process. It should still be available for use via the
LD_PRELOAD trick on various architectures, but using it as the default allocator
for everything would require guaranteeing that it works in all situtations,
which it currently doesn't.

Closes #9925
Remove the fmt! syntax extension

It lived a good life, but its time has come. The groundwork is set for the
official transition after the next snapshot (removal of XXX2 macros)
auto merge of #9856 : alexcrichton/rust/privacy-errors, r=huonw

This stops labeling everything as "is private" when in fact the destination may
be public. Instead, the clause "is inaccessible" is used and the private part of
the flag is called out with a "is private" message.

Closes #9793
auto merge of #9919 : alexcrichton/rust/fmt-begone, r=huonw

It lived a good life, but its time has come. The groundwork is set for the
official transition after the next snapshot (removal of XXX2 macros)
auto merge of #9437 : catamorphism/rust/rustpkg-dates, r=alexcrichton

r? @alexcrichton On most platforms, the time granularity is 1 sec or more, so comparing
dates in tests that check whether rebuilding did or didn't happen leads
to spurious failures. Instead, test the same thing by making an output
file read-only and trapping attempts to write to it.
rustpkg: Search for crates in the current directory

As per #8520, find crates in the current working directory even
if it's not a workspace.

Closes #8520
wip