Fix OSS builds (removes 3.12mp build)

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I think it's reasonable to not have an OSS build of 3.12 - in practice nobody is ever going to use this oddity as it requires Meta Python. CinderX with stock CPython is what we expect going forwards.

I'm trying to reconcile a few constraints here without making the code too complicated:
* For PGO with LLVM we need to have llvm-ar installed, but this isn't available on Sandcastle or Ubuntu Latest (on GitHub).
* It's easyish to install GCC on Sandcastle.
* GCC-13 is available on Ubuntu Latest in GitHub but installing another version is annoying because our GitHub workflow for getdeps is autogenerated.
* GCC-13 is sufficient for CinderX + 3.14 but GCC-14 is needed for CinderX + 3.12 (something seems to have been fixed around headers for atomics when mixing C + C++).

So, making GCC-13 a minimum requirement for OSS builds is good enough to get PGO builds working on Sandcastle + GitHub provided we only target 3.14+.

Reviewed By: itamaro

Differential Revision: D88570106

fbshipit-source-id: 7151be4bda9f754d296bf56f20fba90615918a54

Author: jbower-fb

.github/workflows/getdeps-3_12mp-linux.yml

@@ -30,6 +30,8 @@
 SOURCE_DIR = os.path.join(CHECKOUT_ROOT_DIR, "cinderx")
 PYTHON_LIB_DIR = os.path.join(SOURCE_DIR, "PythonLib")
 
+MIN_GCC_VERSION = 13
+
 
 @lru_cache(maxsize=1)
 def get_compiler() -> tuple[str, str]:
@@ -63,11 +65,13 @@ def get_compiler() -> tuple[str, str]:
                 major_version = int(match.group(1))
                 print(f"Found GCC version {major_version}.{match.group(2)}")
 
-                if major_version >= 14:
+                if major_version >= MIN_GCC_VERSION:
                     print(f"Using GCC: {gcc_path}, {gxx_path}")
                     return (gcc_path, gxx_path)
                 else:
-                    print(f"GCC version {major_version} < 14, checking for Clang")
+                    print(
+                        f"GCC version {major_version} < {MIN_GCC_VERSION}, checking for Clang"
+                    )
         except (subprocess.SubprocessError, subprocess.TimeoutExpired) as e:
             print(f"Failed to determine GCC version: {e}, checking for Clang")