Get rid of yet another fixed size buffer in cg_merge.


git-svn-id: svn://svn.valgrind.org/valgrind/branches/BUF_REMOVAL@14357 a5019735-40e9-0310-863c-91ae7b9d1cf9
Change the readline function to return the line read. That
is quite natural and also eliminates a global variable. The
line is now allocated dynamically.


git-svn-id: svn://svn.valgrind.org/valgrind/branches/BUF_REMOVAL@14358 a5019735-40e9-0310-863c-91ae7b9d1cf9
Remove benign macro redefinition.


git-svn-id: svn://svn.valgrind.org/valgrind/branches/BUF_REMOVAL@14359 a5019735-40e9-0310-863c-91ae7b9d1cf9