More symbol exports and C-API example
base/bool.jl: `-0.0 + false === -0.0`.
Fix jl_apply_array_type (root boxed dim)
remove explicit paths, and gnutar assumption
move tar check to Make.inc and update tar commands
test for compatible tar, error if not found
Skip unicode tests if `iconv --version` fails
Add instructions for windows users
add norm=... keyword argument to quadgk for changing the desired error norm (see JuliaLang/ODE.jl#7)
Extract OPENBLAS_BUILD_OPTS modification for separate PR
Merge pull request #5567 from JuliaLang/sf/qbit_tarfix

Merge testing for compatible tar executables
Map amd64 -> x86_64 in Make.inc
Fix search for bsdtar

Using `tar --help` on `bsdtar` doesn't show a `--strip-components` option like the GNU version (though it does show in the man page. Instead, explicitly check either for `strip-components` or `bsdtar`, which has supported strip-components for the same timeframe as GNU tar, with full support ~2006 for both.
Merge pull request #5569 from scw/patch-1

Fix search for bsdtar
Iteration over ENV (singleton of EnvHash Dict) returned a SubString
instead of a ByteString.  E.g. isequal(ENV,ENV) threw an error.

Now fixed.
Merge pull request #5544 from JuliaLang/sf/iconvskip

Skip unicode tests if `iconv --version` fails
Fix Issue #5581
Merge pull request #5580 from mauro3/ENVgetBug

Iteration over ENV returns wrong type
Merge pull request #5583 from jakebolewski/jb/fix5581

Fix Issue #5581
base/pkg/git.jl: don't shell out to find .git dir [fixes #4888]