cmake: refactor generate-adios2-config.sh

cmake/install/post/generate-adios2-config.sh.in

@@ -4,6 +4,8 @@
 unset MAKEFLAGS
 unset MAKE
 
+declare PREFIX
+
 function make_target_flags() {
   local tgt=$1
   sleep 1
@@ -58,22 +60,15 @@ function prefixify() {
   echo "$@" | sed "s|${PREFIX}|\${ADIOS2_PREFIX}|g"
 }
 
-PREFIX="$1"
+ARG_PREFIX="$1"
 
-if [ "${1:0:1}" != "/" ]
+if [ "${ARG_PREFIX:0:1}" != "/" ] && [ -z "$DESTDIR" ]
 then
-  # Convert relative paths to absolute based on DESTDIR
-  PREFIX="${DESTDIR:-$(pwd)}/$1"
+  PREFIX="$PWD/$ARG_PREFIX"
 else
-  # Check if the DESTDIR directory exists and prepend it to PREFIX
-  if [ -d "${DESTDIR}" ]
-  then
-    PREFIX="${DESTDIR}$1"
-  fi
+  PREFIX="$DESTDIR/$ARG_PREFIX"
 fi
 
-shift
-
 CMAKE="@CMAKE_COMMAND@"
 SOURCE_DIR="@ADIOS2_SOURCE_DIR@/cmake/install/post/adios2-config-dummy"
 BUILD_DIR=$(mktemp -d)