pixman: bump to version 0.38.0

pixman: bump to version 0.38.0

Release 0.37.0 was not actually released.  From the git log, there are
two functional changes about optimization by using float points directly

	Bump version to 0.38.0
	pixman: Use maximum precision for pixman-bits-image, v2.
	Implement floating point gradient computation, v2.
	build: Add meson files to EXTRA_DIST
	editorconfig: use tabs for Makefiles
	Merge remote-tracking branch 'origin/master'
	Post release version bump to 37.1
	gitlab-ci: Add meson build to pipeline test
	meson: Add a meson build system
	Add .editorconfig file
	Bump version to 0.36.0

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>