Dynamically link AWS-LC in cpython integration tests (#2545)

Dynamically link AWS-LC to CPython's main branch integration test to
match [the new upstream CI
job](python/cpython#135402 (comment)).

Author: WillChilds-Klein

tests/ci/integration/python_patch/main/aws-lc-cpython.patch

@@ -207,9 +207,18 @@ cd ${SCRATCH_FOLDER}
 
 mkdir -p ${AWS_LC_BUILD_FOLDER} ${AWS_LC_INSTALL_FOLDER}
 
+# Link AWS-LC dynamically against CPython's main, statically against
+# versioned releases.
+if [[ "${1}" == "main" ]]; then
+    BUILD_SHARED_LIBS="ON"
+    export LD_LIBRARY_PATH="${AWS_LC_INSTALL_FOLDER}/lib"
+else
+    BUILD_SHARED_LIBS="OFF"
+fi
+
 aws_lc_build ${SRC_ROOT} ${AWS_LC_BUILD_FOLDER} ${AWS_LC_INSTALL_FOLDER} \
     -DBUILD_TESTING=OFF \
-    -DBUILD_SHARED_LIBS=0 \
+    -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS} \
     -DFIPS=${FIPS}
 
 fetch_crt_python
@@ -221,6 +230,8 @@ pushd ${PYTHON_SRC_FOLDER}
 which sysctl && ( sysctl -w net.ipv6.conf.all.disable_ipv6=0 || /bin/true )
 echo 0 >/proc/sys/net/ipv6/conf/all/disable_ipv6 || /bin/true
 
+export LD_LIBRARY_PATH="${AWS_LC_INSTALL_FOLDER}/lib"
+
 # NOTE: As we add more versions to support, we may want to parallelize here
 for branch in "$@"; do
     python_patch ${branch}