ninja backend: Fix usage of same constants file for native and cross

For example:
```
meson builddir \
        --native-file vs2019-paths.txt \
        --native-file vs2019-win-x64.txt \
        --cross-file vs2019-paths.txt \
        --cross-file vs2019-win-arm64.txt
```
This was causing the error:

> ERROR: Multiple producers for Ninja target "/path/to/vs2019-paths.txt". Please rename your targets.

Fix it by using a set() when generating the list of regen files, and
add a test for it too.

1 files changed, 7 insertions, 7 deletions

diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 51ca7a0..4a7fbb5 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -2368,7 +2368,7 @@ class AllPlatformTests(BasePlatformTests):
                 endian = 'little'
                 '''.format(os.path.join(testdir, 'cross_pkgconfig.py'))))
             crossfile.flush()
-            self.meson_cross_file = crossfile.name
+            self.meson_cross_files = [crossfile.name]
 
         env = {'PKG_CONFIG_LIBDIR':  os.path.join(testdir,
                                                   'native_pkgconfig')}
@@ -2396,7 +2396,7 @@ class AllPlatformTests(BasePlatformTests):
                 endian = 'little'
                 '''.format(os.path.join(testdir, 'cross_pkgconfig'))))
             crossfile.flush()
-            self.meson_cross_file = crossfile.name
+            self.meson_cross_files = [crossfile.name]
 
         env = {'PKG_CONFIG_LIBDIR':  os.path.join(testdir,
                                                   'native_pkgconfig')}
@@ -2630,8 +2630,8 @@ class AllPlatformTests(BasePlatformTests):
         testdir = os.path.join(self.unit_test_dir, '70 cross')
         # Do a build to generate a cross file where the host is this target
         self.init(testdir, extra_args=['-Dgenerate=true'])
-        self.meson_cross_file = os.path.join(self.builddir, "crossfile")
-        self.assertTrue(os.path.exists(self.meson_cross_file))
+        self.meson_cross_files = [os.path.join(self.builddir, "crossfile")]
+        self.assertTrue(os.path.exists(self.meson_cross_files[0]))
         # Now verify that this is detected as cross
         self.new_builddir()
         self.init(testdir)
@@ -3595,14 +3595,14 @@ class AllPlatformTests(BasePlatformTests):
                 '''))
 
         # Test native C stdlib
-        self.meson_native_file = machinefile
+        self.meson_native_files = [machinefile]
         self.init(testdir)
         self.build()
 
         # Test cross C stdlib
         self.new_builddir()
-        self.meson_native_file = None
-        self.meson_cross_file = machinefile
+        self.meson_native_files = []
+        self.meson_cross_files = [machinefile]
         self.init(testdir)
         self.build()