configure: toolchain-tsan does not need -fPIE.

Fixes compilation with some kernel-gcc combinations:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67308

Reported and analyzed by Gonzalo Garramuño.

configure

@@ -3973,8 +3973,8 @@ case "$toolchain" in
     ;;
     *-tsan)
         cc_default="${toolchain%-tsan}"
-        add_cflags  -fsanitize=thread -fPIE
-        add_ldflags -fsanitize=thread -pie
+        add_cflags  -fsanitize=thread
+        add_ldflags -fsanitize=thread
         case "$toolchain" in
             gcc-tsan)
                 add_cflags  -fPIC