gh-113330: Fix mimalloc headers reference (#113331)

The `MIMALLOC_HEADERS` variable is defined in the Makefile.pre.in, not
the configure script, so we should use the `$(MIMALLOC_HEADERS)` syntax
instead of the `@MIMALLOC_HEADERS@` syntax.

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 95b2f246ed5bcbaddcecfe1b8b6587950e4d8a8e..4e2ec974b79eeaf49c1945a03e45852bd794d75e 100644 (file)
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1797,7 +1797,7 @@ PYTHON_HEADERS= \
                $(srcdir)/Include/cpython/warnings.h \
                $(srcdir)/Include/cpython/weakrefobject.h \
                \
-               @MIMALLOC_HEADERS@ \
+               $(MIMALLOC_HEADERS) \
                \
                $(srcdir)/Include/internal/pycore_abstract.h \
                $(srcdir)/Include/internal/pycore_asdl.h \