build-llvm: Avoid hardcoding the python version number in this script

This eases updating the build to a newer version of python.

build-llvm.sh

@@ -203,21 +203,23 @@ if [ -n "$HOST" ]; then
     BUILDDIR=$BUILDDIR-$HOST
 
     if [ -n "$WITH_PYTHON" ]; then
-        PYTHON_VER="3.9"
         # The python3-config script requires executing with bash. It outputs
         # an extra trailing space, which the extra 'echo' layer gets rid of.
         EXT_SUFFIX="$(echo $(bash $PREFIX/python/bin/python3-config --extension-suffix))"
+        PYTHON_RELATIVE_PATH="$(cd "$PREFIX" && echo python/lib/python*/site-packages)"
+        PYTHON_INCLUDE_DIR="$(echo $PREFIX/python/include/python*)"
+        PYTHON_LIB="$(echo $PREFIX/python/lib/libpython*.dll.a)"
         CMAKEFLAGS="$CMAKEFLAGS -DLLDB_ENABLE_PYTHON=ON"
         CMAKEFLAGS="$CMAKEFLAGS -DPYTHON_HOME=$PREFIX/python"
         CMAKEFLAGS="$CMAKEFLAGS -DLLDB_PYTHON_HOME=../python"
         # Relative to the lldb install root
-        CMAKEFLAGS="$CMAKEFLAGS -DLLDB_PYTHON_RELATIVE_PATH=python/lib/python$PYTHON_VER/site-packages"
+        CMAKEFLAGS="$CMAKEFLAGS -DLLDB_PYTHON_RELATIVE_PATH=$PYTHON_RELATIVE_PATH"
         # Relative to LLDB_PYTHON_HOME
         CMAKEFLAGS="$CMAKEFLAGS -DLLDB_PYTHON_EXE_RELATIVE_PATH=bin/python3.exe"
         CMAKEFLAGS="$CMAKEFLAGS -DLLDB_PYTHON_EXT_SUFFIX=$EXT_SUFFIX"
 
-        CMAKEFLAGS="$CMAKEFLAGS -DPython3_INCLUDE_DIRS=$PREFIX/python/include/python$PYTHON_VER"
-        CMAKEFLAGS="$CMAKEFLAGS -DPython3_LIBRARIES=$PREFIX/python/lib/libpython$PYTHON_VER.dll.a"
+        CMAKEFLAGS="$CMAKEFLAGS -DPython3_INCLUDE_DIRS=$PYTHON_INCLUDE_DIR"
+        CMAKEFLAGS="$CMAKEFLAGS -DPython3_LIBRARIES=$PYTHON_LIB"
     fi
 elif [ -n "$STAGE2" ]; then
     # Build using an earlier built and installed clang in the target directory