merge bitcoin#26470: Clean up libexec/build.sh

contrib/guix/libexec/build.sh

@@ -71,16 +71,12 @@ unset CPLUS_INCLUDE_PATH
 unset OBJC_INCLUDE_PATH
 unset OBJCPLUS_INCLUDE_PATH
 
-export LIBRARY_PATH="${NATIVE_GCC}/lib:${NATIVE_GCC}/lib64:${NATIVE_GCC_STATIC}/lib:${NATIVE_GCC_STATIC}/lib64"
+export LIBRARY_PATH="${NATIVE_GCC}/lib:${NATIVE_GCC_STATIC}/lib"
 export C_INCLUDE_PATH="${NATIVE_GCC}/include"
 export CPLUS_INCLUDE_PATH="${NATIVE_GCC}/include/c++:${NATIVE_GCC}/include"
 export OBJC_INCLUDE_PATH="${NATIVE_GCC}/include"
 export OBJCPLUS_INCLUDE_PATH="${NATIVE_GCC}/include/c++:${NATIVE_GCC}/include"
 
-prepend_to_search_env_var() {
-    export "${1}=${2}${!1:+:}${!1}"
-}
-
 # Set environment variables to point the CROSS toolchain to the right
 # includes/libs for $HOST
 case "$HOST" in