Add .gitignore everywhere based on .cvsignore.

* .gitignore: New.
* build-aux/.gitignore: New.
* data/.gitignore: New.
* doc/.gitignore: New.
* etc/.gitignore: New.
* examples/.gitignore: New.
* examples/calc++/.gitignore: New.
* lib/.gitignore: New.
* m4/.gitignore: New.
* po/.gitignore: New.
* runtime-po/.gitignore: New.
* src/.gitignore: New.
* tests/.gitignore: New.

tests/.gitignore

@@ -0,0 +1,16 @@
+/*.dot
+/*.output
+/atconfig
+/atlocal
+/autom4te.cache
+/bison
+/calc
+/calc.[chy]
+/calc.tab.*
+/Makefile
+/Makefile.in
+/Makefile.in
+/package.m4
+/testsuite
+/testsuite.dir
+/testsuite.log