delete autotools .gitignore files

One special case, `src/util/xmlpool/.gitignore` is not entirely deleted,
as `xmlpool.pot` still gets generated (eg. by `ninja xmlpool-pot`).

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>

src/compiler/glsl/tests/.gitignore

@@ -1,6 +0,0 @@
-blob-test
-cache-test
-ralloc-test
-uniform-initializer-test
-sampler-types-test
-general-ir-test

src/compiler/glsl/tests/warnings/.gitignore

@@ -1 +0,0 @@
-/*.out