[compiler-rt] [test] Avoid error printouts if os.sysconf is missing (#168857)

This avoids dozens of instances of benign error messages being printed
when running the tests on e.g. Windows:

    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: module 'os' has no attribute 'sysconf'

Co-authored-by: Florian Mayer <[email protected]>

Author: mstorsjo

compiler-rt/test/lit.common.cfg.py

@@ -971,7 +971,9 @@ def target_page_size():
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
         )
-        out, err = proc.communicate(b'import os; print(os.sysconf("SC_PAGESIZE"))')
+        out, err = proc.communicate(
+            b'import os; print(os.sysconf("SC_PAGESIZE") if hasattr(os, "sysconf") else "")'
+        )
         return int(out)
     except:
         return 4096