Environment: Fix passing envrionment variables CPPFLAGS and CFLAGS

Or other language flags that use CPPFLAGS (like CXXFLAGS). The problem
here is actually rather simple, `dict.setdefault()` doesn't work like I
thought it did, I thought it created a weak entry, but it actually is
equivalent to:
```python
if k not in dict:
    dict[k] = v
```
Instead we'll use an intermediate dictionary (a default dictionary
actually, since that makes things a little cleaner) and then add the
keys from that dict to self.options as applicable.

Test case written by Jussi, Fix by Dylan

Co-authored-by: Jussi Pakkanen
Fixes: #8361
Fixes: #8345

1 files changed, 0 insertions, 1 deletions

diff --git a/mesonbuild/mesonlib/universal.py b/mesonbuild/mesonlib/universal.py
index 7deb24a..19e329d 100644
--- a/mesonbuild/mesonlib/universal.py
+++ b/mesonbuild/mesonlib/universal.py
@@ -2023,7 +2023,6 @@ class OptionKey:
         This takes strings like `mysubproject:build.myoption` and Creates an
         OptionKey out of them.
         """
-
         try:
             subproject, raw2 = raw.split(':')
         except ValueError: