patch 8.2.2089: libvterm test fails to build on Mac

Problem:    Libvterm test fails to build on Mac.
Solution:   Adjust configure to remove a space between -L and the path that
            follows.
diff --git a/src/configure.ac b/src/configure.ac
index 010cc8f..4b6794a 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -4467,6 +4467,10 @@
   AC_MSG_RESULT(no)
 fi
 
+dnl $LDFLAGS is passed to glibtool in libvterm, it doesn't like a space
+dnl between "-L" and the path that follows.
+LDFLAGS=`echo "$LDFLAGS" | sed -e 's/-L /-L/g'`
+
 dnl link.sh tries to avoid overlinking in a hackish way.
 dnl At least GNU ld supports --as-needed which provides the same functionality
 dnl at linker level. Let's use it.