Update Makefile

1. Preserve the timestamp by replacing cp with install -p
2. Restrict file permissions by install -m
mkdir -p $(DESTDIR)$(SYSCONFDIR)

mkdir -p $(DESTDIR)$(SYSCONFDIR)
Update $(DESTDIR)$(PREFIX) in comments

--- we always install to PREFIX/etc.
+++ we always install to $(DESTDIR)$(PREFIX)/etc.
expm: fixed rescaling
support multiple/matrix right-hand sides in sparse A \ B
adds section on passing pointers to C functions for modification
Use debug executable on Travis
Use openspecfun.
Amos and Faddeeva were moved out of openlibm.
libopenlibm-extras is now libopenspecfun.
Merge pull request #5137 from JuliaLang/vs/olm-extras

WIP: openspecfun
Fix #5169
Merge pull request #5228 from JuliaLang/debugtravis

Use debug executable on Travis
Merge pull request #5213 from ssfrr/master

adds section on passing pointers to C functions for modification
Rename and move the section on passing pointers for modifying inputs.
Merge pull request #5196 from stevengj/sparse_ldiv_matrix

support multiple/matrix right-hand sides in sparse A \ B
Add complex(sparse) and complex(sparse,sparse)
Fix multiple RHS sparse(a) \ b
Add tests for #5196, multiple RHS sparse(A) \ b
Fix a size bug in bwdTriSolve
Merge pull request #5151 from acroy/expm-scaling

RFC: fixed rescaling in expm (issue 5116)
Add tests for expm balancing issue (#5151)
Merge branch 'patch-1' of github.com:cicku/julia into cicku-patch-1

Conflicts:
	Makefile
INSTALL_B does not exist. Use INSTALL_M instead.