Fix find() when called with function and non-StridedArray

The previous code expected testfun to be vectorized, which does not match
the behavior of other methods, nor the documentation. Especially visible
when passing a sparse matrix. Always return an Array rather than an object
similar to the input, because it makes no sense to return a sparse vector.
Remove the method matching any object so that an error is raised rather
than returning incorrect results on non-AbstractArray (e.g. Set).
fix bounds bug in getindex(a:b, c:d) with c<1

And more laconic Julia.

Commit 646fe6b3 eliminated a non "redundant bounds check", which is here
re-introduced via `check_indexingrange` function.
fall back on apropos if help fails; partially fixes #8262
check indices in sparsevec(::Dict). fixes #8363
Merge pull request #8373 from tanmaykm/fix8363

check indices in sparsevec(::Dict). fixes #8363
Merge pull request #8351 from rfourquet/range-getindex

fix bounds bug in getindex(a:b, c:d) with c<1
membuf is now a std::unique_ptr in llvm3.6
Merge pull request #8327 from davidssmith/help

fall back on apropos() if help() fails; fixes #8262
Merge pull request #8374 from jakebolewski/jcb/fixllvm36osx

llvm-3.6 getMemBuffer now returns a std::unique_ptr<MemoryBuffer>
Update base.rst
Update helpdb.jl
Merge pull request #8376 from apeyser/master

 Suggestion: add to whos() documentation that it only displays exported variables #8375
add DATAROOTDIR to build_h.jl, use it in Base.runtests()
deprecate randbool! and add rand(Bool). fixes #8377
Merge pull request #8323 from nalimilan/find

Fix find() when called with function and non-StridedArray
added built-in exception UndefVarError to manual
Merge pull request #8386 from davidssmith/man

added built-in exception UndefVarError to manual
close #8304, tweak openblas build troubleshooting

this is a bit redundant, but it definitely belongs under the category of openblas build failure
Bump libosxunwind to 0.0.1. (RC3 was marked as release).
move default setting of prefix to Make.inc,

change SYSCONFDIR and DATAROOTDIR to be relative paths