Ninja: Use OrderedDict in places where order matters

Specifically, wherever we have sources or outputs, we want to use an
OrderedDict so that the build is always deterministic. It was reported
by Olexa Bilaniuk that `ar D` creates static libraries with different
checksums depending on the order of the object files.

See: https://github.com/mesonbuild/meson/pull/951

We don't actually want to preserve the order in which they are listed.
We just want the order to be deterministic and predictable.

mesonbuild/backend/ninjabackend.py

@@ -23,6 +23,7 @@ from .backends import InstallData
 from ..build import InvalidArguments
 import os, sys, pickle, re
 import subprocess, shutil
+from collections import OrderedDict
 
 if mesonlib.is_windows():
     quote_char = '"'
@@ -239,7 +240,7 @@ int dummy;
         (relative to the build directory) of that type and the value
         being the GeneratorList or CustomTarget that generated it.
         """
-        srcs = {}
+        srcs = OrderedDict()
         for gensrc in target.get_generated_sources():
             for s in gensrc.get_outputs():
                 f = self.get_target_generated_dir(target, gensrc, s)
@@ -247,7 +248,7 @@ int dummy;
         return srcs
 
     def get_target_sources(self, target):
-        srcs = {}
+        srcs = OrderedDict()
         for s in target.get_sources():
             # BuildTarget sources are always mesonlib.File files which are
             # either in the source root, or generated with configure_file and
@@ -300,10 +301,10 @@ int dummy;
 
         # Pre-existing target C/C++ sources to be built; dict of full path to
         # source relative to build root and the original File object.
-        target_sources = {}
+        target_sources = OrderedDict()
         # GeneratedList and CustomTarget sources to be built; dict of the full
         # path to source relative to build root and the generating target/list
-        generated_sources = {}
+        generated_sources = OrderedDict()
         # Array of sources generated by valac that have to be compiled
         vala_generated_sources = []
         if 'vala' in target.compilers:
@@ -939,10 +940,10 @@ int dummy;
         the keys being the path to the file (relative to the build directory)
         and the value being the object that generated or represents the file.
         """
-        vala = {}
-        vapi = {}
-        others = {}
-        othersgen = {}
+        vala = OrderedDict()
+        vapi = OrderedDict()
+        others = OrderedDict()
+        othersgen = OrderedDict()
         # Split pre-existing sources
         for s in t.get_sources():
             # BuildTarget sources are always mesonlib.File files which are
@@ -1088,7 +1089,7 @@ int dummy;
         args += ['--out-dir', target.subdir]
         args += ['--emit', 'dep-info', '--emit', 'link']
         orderdeps = [os.path.join(t.subdir, t.get_filename()) for t in target.link_targets]
-        linkdirs = {}
+        linkdirs = OrderedDict()
         for d in target.link_targets:
             linkdirs[d.subdir] = True
         for d in linkdirs.keys():