.gitignore: globally ignore .la files

With automake and libraries, these files are creeping in.

.gitignore

@@ -1,6 +1,7 @@
 *.o
 *.lo
 *.a
+*.la
 *.in
 *.[ch]e
 *.log

examples/plugins/c-json-filetype/.gitignore

@@ -1,3 +1,2 @@
 !/Makefile.in
 *.so
-*.la

examples/plugins/ci-capture/.gitignore

@@ -1,4 +1,3 @@
 !/Makefile.in
 *.o
 *.so
-*.la