Owen Ou 161ab0402b Fix typo in CI env vars for Linux build (#2810) ...

For some reason, the env vars are set correctly without refering the variable in `matrix` case-sensitvely:

```
2023-08-01T05:05:58.4626090Z env:
2023-08-01T05:05:58.4626367Z   AR: arm-linux-gnueabihf-ar
2023-08-01T05:05:58.4626690Z   CHOST: arm-linux-gnueabihf
2023-08-01T05:05:58.4626961Z   CC: arm-linux-gnueabihf-gcc
2023-08-01T05:05:58.4627332Z   CPP: arm-linux-gnueabihf-cpp
2023-08-01T05:05:58.4627662Z   CXX: arm-linux-gnueabihf-g++
```

For clarify, we update them to match the definitions. Besides, `CXX` is
not needed and removed.

2023-08-01 07:32:52 -07:00

..

ci.yml

…

decnum.yml

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manpage.yml

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oniguruma.yml

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scanbuild.yml

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valgrind.yml

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website.yml

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