When sources are included within debug information, a couple of areas of the 
qemu build are not reproducible due to either full buildpaths or timestamps.

Replace the full paths with relative ones. I couldn't figure out how to get
meson to pass relative paths but we can fix that in the script.

For the keymaps, omit the timestamps as they don't matter to us.

Upstream-Status: Pending [some version of all/part of this may be accepted]
RP 2021/3/1

Index: qemu-5.2.0/scripts/decodetree.py
===================================================================
--- qemu-5.2.0.orig/scripts/decodetree.py
+++ qemu-5.2.0/scripts/decodetree.py
@@ -1303,8 +1303,8 @@ def main():
     toppat = ExcMultiPattern(0)
 
     for filename in args:
-        input_file = filename
-        f = open(filename, 'r')
+        input_file = os.path.relpath(filename)
+        f = open(input_file, 'r')
         parse_file(f, toppat)
         f.close()
 
Index: qemu-5.2.0/ui/keycodemapdb/tools/keymap-gen
===================================================================
--- qemu-5.2.0.orig/ui/keycodemapdb/tools/keymap-gen
+++ qemu-5.2.0/ui/keycodemapdb/tools/keymap-gen
@@ -317,9 +317,8 @@ class LanguageGenerator(object):
         raise NotImplementedError()
 
     def generate_header(self, database, args):
-        today = time.strftime("%Y-%m-%d %H:%M")
         self._boilerplate([
-            "This file is auto-generated from keymaps.csv on %s" % today,
+            "This file is auto-generated from keymaps.csv",
             "Database checksum sha256(%s)" % database.mapchecksum,
             "To re-generate, run:",
             "  %s" % args,