Make version_git.sh work on older versions of git.

The --count option to git-rev-list was introduced in git version 1.7.x
for 1 < x < 12. When base/version_git.sh is run on versions of git
without this option, a long help message is generated (cluttering up
make output) and generating an incorrect base/version_git.jl.
version_git.sh: cope with wcs that emit whitespace.

Some versions of wc (notably the one supplied by OS X) prepend
whitespace to the output of `wc -l`, breaking the indentation of the
generated version_git.jl. We strip this using only tr(1) features
specified in
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/tr.html.
Replace calls to tr with calls to sed

We're already using sed elsewhere in the script.
RFC: Add RNG argument to randn (random normals)
Document variants of LU and QR factorizations in manual
add jl_is_nothing predicate

Julia C API is lacking in a predicate to check if a given value is
nothing or not. This commit includes the predicate in C macro.
Merge branch 'master' of https://github.com/JuliaLang/julia
Merge pull request #6111 from jperla/randn

RFC: Add RNG argument to randn (random normals)
Fix pointer-type deprecation in peekchar
Fix whitespace in uniformscaling.jl
correct spelling of 'parameterized'
Merge pull request #6189 from catawbasam/patch-2

correct spelling of 'parameterized'
Merge branch 'master' of https://github.com/JuliaLang/julia
Merge pull request #6186 from bicycle1885/is_nothing

add jl_is_nothing predicate
add conversions from float to BigInt. ref #6183
Merge pull request #6066 from pozorvlak/old_git

Make version_git.sh work on older versions of git.
Merge branch 'master' of github.com:JuliaLang/julia
Avoid SharedArray failures if IP changes

Fix #6171
fix #6175

bug in marking return type of void calls
Use debug flisp/support in debug julia. Part of #5774