Configure problem (and fix).

I have come across a problem where the code generated by autoconf does not
subsitute correct values for the following variables:

bindir sbindir libexecdir
datadir sysconfdir sharedstatedir
localstatedir libdir includedir
oldincludedir infodir mandir

The problem is that they reference the variables, 'prefix' and 'exec_prefix'
but those variables are not expanded in the subsitutions. For example,
referencing 'libdir' in an *.in file will have "${exec_prefix}/lib" placed in
the resulting output file. It should be "/usr/local/pgsql/lib" (if the
default exec_prefix (and prefix) value is used). The first patch
(uw7-1.patch) will correct the problem, which causes an incorrect
src/pl/plpgsql/src/mklang.sql file to be generated.

The second patch:

1. Adds a file (mklang.sql) that can be used to add the language
definitions for PL/TCL to a database.

2. Generalizes the mklang.sql in src/pl/plpgsql/test so that it will
reference the correct location for the plpgsql.so shared library.

3. Generalizes the test_mklang.sql file in src/pl/tcl/test so that is will
reference the correct localtion for the pltcl.so shared library.

IMPORTANT: Do not apply the second patch without applying the first patch!