Move submodule init before aarch64 workaround, deduplicate UNAME_S

Move submodule initialization above the aarch64 sed workaround so
the file it edits is guaranteed to exist even if the caller disables
submodule checkout. Also remove the redundant UNAME_S assignment
later in the script.

Author: manuelcandales

.ci/scripts/wheel/pre_build_script.sh

@@ -9,18 +9,6 @@ set -euxo pipefail
 
 # This script is run before building ExecuTorch binaries
 
-if [[ "$(uname -m)" == "aarch64" ]]; then
-  # On some Linux aarch64 systems, the "atomic" library is not found during linking.
-  # To work around this, replace "atomic" with the literal ${ATOMIC_LIB} so the
-  # build system uses the full path to the atomic library.
-  file="extension/llm/tokenizers/third-party/sentencepiece/src/CMakeLists.txt"
-  sed 's/list(APPEND SPM_LIBS "atomic")/list(APPEND SPM_LIBS ${ATOMIC_LIB})/' \
-    "$file" > "${file}.tmp" && mv "${file}.tmp" "$file"
-
-  grep -n 'list(APPEND SPM_LIBS ${ATOMIC_LIB})' "$file" && \
-    echo "the file $file has been modified for atomic to use full path"
-fi
-
 # Initialize submodules here instead of during checkout so we can use OpenSSL
 # on Windows (schannel fails with SEC_E_ILLEGAL_MESSAGE on some gitlab hosts).
 UNAME_S=$(uname -s)
@@ -42,9 +30,20 @@ else
 fi
 popd
 
+if [[ "$(uname -m)" == "aarch64" ]]; then
+  # On some Linux aarch64 systems, the "atomic" library is not found during linking.
+  # To work around this, replace "atomic" with the literal ${ATOMIC_LIB} so the
+  # build system uses the full path to the atomic library.
+  file="extension/llm/tokenizers/third-party/sentencepiece/src/CMakeLists.txt"
+  sed 's/list(APPEND SPM_LIBS "atomic")/list(APPEND SPM_LIBS ${ATOMIC_LIB})/' \
+    "$file" > "${file}.tmp" && mv "${file}.tmp" "$file"
+
+  grep -n 'list(APPEND SPM_LIBS ${ATOMIC_LIB})' "$file" && \
+    echo "the file $file has been modified for atomic to use full path"
+fi
+
 # On Windows, enable symlinks and re-checkout the current revision to create
 # the symlinked src/ directory. This is needed to build the wheel.
-UNAME_S=$(uname -s)
 if [[ $UNAME_S == *"MINGW"* || $UNAME_S == *"MSYS"* ]]; then
     echo "Enabling symlinks on Windows"
     git config core.symlinks true