Checking in this patch for Thiago: Rename python-* files into py-*,

Checking in this patch for Thiago: Rename python-* files into py-*,
more 8+3 friendly.

gdb/
        * Makefile.in (py-cmd.o): Renamed from python-cmd.o.  Updated
        references.
        (py-frame.o): Renamed from python-frame.o.  Updated references.
        (py-function.o): Renamed from python-function.o.  Updated references.
        (py-objfile.o): Renamed from python-objfile.o.  Updated references.
        (py-prettyprint.o): Renamed from python-prettyprint.o.  Updated
+references.
        (py-type.o): Renamed from python-type.o.  Updated references.
        (py-utils.o): Renamed from python-utils.o.  Updated references.
        (py-value.o): Renamed from python-value.o.  Updated references.
        * py-cmd.o: Renamed from python-cmd.o.
        * py-frame.o: Renamed from python-frame.o.
        * py-function.o: Renamed from python-function.o.
        * py-objfile.o: Renamed from python-objfile.o.
        * py-prettyprint.o: Renamed from python-prettyprint.o.
        * py-type.o: Renamed from python-type.o.
        * py-utils.o: Renamed from python-utils.o.
        * py-value.o: Renamed from python-value.o.

gdb/testsuite/
        * gdb.python/Makefile.in (EXECUTABLES): Adjust to new executable
        names, add missing ones.
        * gdb.python/py-cmd.exp: Rename from python-cmd.exp.
        * gdb.python/py-frame.c: Rename from python-frame.c.
        * gdb.python/py-frame.exp: Rename from python-frame.exp.  Adjust
        testfile name.
        * gdb.python/py-function.exp: Rename from python-function.exp.
        * gdb.python/py-mi.exp: Rename from python-mi.exp.  Adjust
        testfile name.
        * gdb.python/py-prettyprint.c: Rename from python-prettyprint.c.
        * gdb.python/py-prettyprint.exp: Rename from python-prettyprint.exp.
        Adjust testfile name.
        * gdb.python/py-prettyprint.py: Rename from python-prettyprint.py.
        * gdb.python/py-template.cc: Rename from python-template.cc.
        * gdb.python/py-template.exp: Rename from python-template.exp.
        Adjust testfile name.
        * gdb.python/py-value.c: Rename from python-value.c.
        * gdb.python/py-value.exp: Rename from python-value.exp.  Adjust
        testfile name.