drm: implement syncobj and fence for VIRGL/VirtIO driver

Extract protocol-agnostic FenceTimeline from Intel to shared
src/drivers/fence.rs — atomic-based fence tracking suitable
for Intel, VIRGL, and AMD drivers.

Extract protocol-agnostic SyncobjManager from Intel to shared
src/drivers/syncobj.rs — syncobj create/destroy/signal/reset/
wait/query and sync_file fd export/import.

Wire both into VirtioDriver:
- Add FenceTimeline + SyncobjManager fields
- Implement all 5 GpuDriver syncobj trait methods
  (create, destroy, wait, export_fd, import_fd)
- Track fence seqnos in virgl_submit_3d (allocate
  before submit, signal after completion)

Intel fence.rs and syncobj.rs converted to thin re-export
modules pointing at shared sources — no behavioral change
for Intel driver.

This gives Mesa VIRGL userspace the standard DRM syncobj
API for GPU/compositor synchronization.

recipes/tools/nano/source/syntax/python.nanorc

@@ -0,0 +1,44 @@
+## Syntax highlighting for Python.
+
+syntax python "\.py$"
+header "^#!.*python"
+magic "Python script"
+comment "#"
+
+# Alternative linter: pylint --exit-zero
+linter pyflakes
+
+# Function definitions.
+color brightblue "def [0-9A-Za-z_]+"
+# Keywords.
+color brightcyan "\<(and|as|assert|async|await|break|class|continue)\>"
+color brightcyan "\<(def|del|elif|else|except|finally|for|from)\>"
+color brightcyan "\<(global|if|import|in|is|lambda|nonlocal|not|or)\>"
+color brightcyan "\<(pass|raise|return|try|while|with|yield)\>"
+
+# These two are keywords in Python 2, but functions in Python 3,
+# so only color them when they are followed by whitespace, assuming
+# that print(x) is a function invocation and print (x) is a statement.
+color brightcyan "\<(exec|print)([[:blank:]]|$)"
+
+# Special values.
+color brightmagenta "\<(False|None|True)\>"
+
+# Mono-quoted strings.
+color brightgreen "'([^'\]|\\.)*'|"([^"\]|\\.)*"|'''|""""
+color normal "'''|""""
+# Comments.
+color brightred "(^|[[:blank:]])#.*"
+# Triple-quoted strings.
+color brightgreen start="'''([^'),]|$)" end="(^|[^(\])'''"
+color brightgreen start=""""([^"),]|$)" end="(^|[^(\])""""
+
+# Backslash escapes.
+color lime "\\($|[\'"abfnrtv]|[0-3]?[0-7]?[0-7]|x[[:xdigit:]]{2})"
+color lime "\\(N\{[[:alpha:]]+\}|u[[:xdigit:]]{4}|U[[:xdigit:]]{8})"
+
+# Reminders.
+color brightwhite,yellow "\<(FIXME|TODO|XXX)\>"
+
+# Trailing whitespace.
+color ,green "[[:space:]]+$"