libstdc++-v3: Fix error in x86_64 zephyr support patch

Way back in 2019, b1bdbab added
x86_64 zephyr support. That included a duplicate line
which causes a syntax error in this file.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

libstdc++-v3/configure.host

@@ -318,7 +318,6 @@ case "${host}" in
  loongarch*)
     tmake_file="cpu/loongarch/t-loongarch"
     ;;
- *-*-linux* | *-*-uclinux*)
  *-zephyr-elf*)
     case "${host_cpu}" in
       i[567]86)