Add new sparse matmul performance tracking test

Existing test for sparse matrix-matrix multiplication is not very representative
Remove scale!{T<:BlasReal}(X::Array{T}, s::Complex)

* Reference: https://github.com/JuliaLang/julia/issues/1868#issuecomment-36004446
Fix scale(X::AbstractArray{Real}, s::Complex)

* after removal of corresponding scale! method
* also add tests
Change get getipaddr to default to loopback

Allows building with no external IP address:

62d0b3d4 introduced a dependency on getipaddr(), which previously raised an error if no
external address was found. This broke bootstrap on a loopback-only network.

closes #5945
removed redundant eltype definitions for darray and sharedarray
Tweaks for cross compiling from Cygwin to MinGW

* Cygwin versions of MinGW compilers put standard libraries in /bin, not /lib
* Blas and Lapack should be in build_shlibdir
* Don't use wine for Cygwin to MinGW cross compile
* New cygpath_w helper function to convert Cygwin paths to Windows-style so MinGW-compiled
executables can understand them
* Use cygpath_w for system image file locations
Fix doc example of @test_approx_eq_eps precision argument 

`e-2` means Euler's number minus two. I guess original author wanted to mean `10^-2`
fix #5966

showcompact() should always be compact; confine the output limit stuff to
array printing
fix #5963
Fix EPIPE error