sdbus++-gen-meson: force locale for stable sort

Locale affects certain tools like `sort`.  Force the locale to
the POSIX ("C") locale for stability no matter what the user has
set.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Id8993f6efcbee1904d8b068ac4bf328a630c0116
diff --git a/tools/sdbus++-gen-meson b/tools/sdbus++-gen-meson
index a156332..27613f2 100755
--- a/tools/sdbus++-gen-meson
+++ b/tools/sdbus++-gen-meson
@@ -2,6 +2,10 @@
 
 set -e
 
+# Locale can change behavior of utilities like 'sort' but we want the output
+# to be stable on all machines.  Force the locale to 'C' for consistency.
+export LC_ALL=C
+
 function show_usage {
     cat \
 <<EOF