unix: emit NEED_LIBRESSL/NEED_OPENSSL in Python

Reading the environment variable is a bit hacky. But it
gets the job done.

Author: indygreg

cpython-unix/Makefile

@@ -44,14 +44,6 @@ ifdef PYBUILD_MUSL
     PLATFORM := $(PLATFORM)-musl
 endif
 
-ifdef PYBUILD_LIBRESSL
-    NEED_LIBRESSL := 1
-    NEED_OPENSSL :=
-else
-    NEED_OPENSSL := 1
-    NEED_LIBRESSL :=
-endif
-
 # Always write out settings files.
 $(shell $(RUN_BUILD) placeholder_archive makefiles)
 include $(OUTDIR)/Makefile.$(TARGET_TRIPLE)

pythonbuild/utils.py

@@ -94,6 +94,11 @@ def write_triples_makefiles(targets, dest_dir: pathlib.Path):
         for need in settings.get("needs", []):
             lines.append("NEED_%s := 1\n" % need.upper())
 
+        if "PYBUILD_LIBRESSL" in os.environ:
+            lines.append("NEED_LIBRESSL := 1\n")
+        else:
+            lines.append("NEED_OPENSSL := 1\n")
+
         write_if_different(makefile_path, "".join(lines).encode("ascii"))