Add perf tests for chap15 and chap16.

Discussed with @ronawho.

git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23855 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
Use PWD instead of WORKSPACE in windows batch script.

WORKSPACE use windows file path separators, which does not translate well to
the cygwin/bash environment. PWD uses the cygwin/bash file separator _and_ it
uses the correct file system mapping.

git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@23856 3a8e244f-b0f2-452b-bcba-4c88e055c3ca