libcamera: Add missing SPDX headers for miscellaneous CC0-1.0 contents

Miscellaneous files that are not considered copyrightable are missing an
SPDX-License-Identifier header. Fix this by adding a header listing the
CC0-1.0 license.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

subprojects/.gitignore

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: CC0-1.0
+
 /googletest-release*
 /libyaml
 /libyuv

subprojects/gtest.wrap

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: CC0-1.0
+
 [wrap-file]
 directory = googletest-release-1.11.0
 source_url = https://github.com/google/googletest/archive/release-1.11.0.zip

subprojects/libyaml.wrap

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: CC0-1.0
+
 [wrap-git]
 directory = libyaml
 url = https://github.com/yaml/libyaml

subprojects/libyuv.wrap

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: CC0-1.0
+
 [wrap-git]
 directory = libyuv
 url = https://chromium.googlesource.com/libyuv/libyuv.git

subprojects/pybind11.wrap

@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: CC0-1.0
+
 [wrap-git]
 url = https://github.com/pybind/pybind11.git
 # This is the head of 'smart_holder' branch