[3.11] [3.12] GH-113516: don't set `LDSHARED` when building for WASI (GH-115495) (GH-115496) (GH-115497)

[3.12] GH-113516: don't set `LDSHARED` when building for WASI (GH-115495) (GH-115496)
(cherry picked from commit 0e4f73b8e457b1efa57b735205e8e85a3d11d9f2)

Co-authored-by: Brett Cannon <brett@python.org>