tests: fix OpenAL test case on case sensitive fs on macOS

Preface: why are we doing this?

For reasons of cross-platform interop, the Lix team is strongly
considering switching to build on a case sensitive filesystem in the
macOS installation, since otherwise storing case overlapping filenames
is busted and requires very very bad hacks:
https://git.lix.systems/lix-project/lix/issues/332

What's wrong:

Command line: `clang++ '/nix/temp/meson/b d01bff197e/meson-private/tmpjqid64j1/testfile.cpp' -o '/nix/temp/meson/b d01bff197e/meson-private/tmpjqid64j1/output.exe' -O0 -fpermissive -Werror=implicit-function-declaration -F/nix/store/qa92ravmclyraw7b46cz3q3m834mmbw9-apple-framework-OpenAL/Library/Frameworks -framework openal` -> 1
stderr:
ld: framework not found openal
clang-16: error: linker command failed with exit code 1 (use -v to see invocation)

Why is that happening:

$ ls /nix/store/qa92ravmclyraw7b46cz3q3m834mmbw9-apple-framework-OpenAL/Library/Frameworks
OpenAL.framework

So the test was relying on case insensitive fs, which is not a reliable
assumption on all macOS installations (since weird people like us can
set their fs to case sensitive!).

test cases/osx/9 framework recasting/meson.build

@@ -1,5 +1,5 @@
 project('framework recasting', 'c', 'cpp')
 
-x = dependency('openal')
+x = dependency('OpenAL')
 
 y = executable('tt', files('main.cpp'), dependencies: x)