bpo-34602: Fix unportable test(1) operator in configure script (GH-30490) (GH-30491)

(cherry picked from commit 3d11c1b) Co-authored-by: Thomas Klausner <tk@giga.or.at>

Author: miss-islington

configure

@@ -9895,7 +9895,7 @@ then
 # small for the default recursion limit. Increase the stack size
 # to ensure that tests don't crash
  stack_size="1000000" # 16 MB
- if test "$with_ubsan" == "yes"
+ if test "$with_ubsan" = "yes"
  then
  # Undefined behavior sanitizer requires an even deeper stack
  stack_size="4000000" # 64 MB

configure.ac

@@ -2816,7 +2816,7 @@ then
 # small for the default recursion limit. Increase the stack size
 # to ensure that tests don't crash
  stack_size="1000000" # 16 MB
- if test "$with_ubsan" == "yes"
+ if test "$with_ubsan" = "yes"
  then
  # Undefined behavior sanitizer requires an even deeper stack
  stack_size="4000000" # 64 MB