gnu: Remove unnecessary closures around `arguments' value.

* gnu/packages/algebra.scm (pari-gp): Remove closure around the value of
  `arguments'.
* gnu/packages/bdb.scm (bdb): Likewise.
* gnu/packages/mit-krb5.scm (mit-krb5): Likewise.
* gnu/packages/openssl.scm (openssl): Likewise.
* gnu/packages/perl.scm (perl): Likewise.