Clean unused DEBUG_CFLAGS variable

The unused DEBUG_CFLAGS variable has been removed from Zend.m4 macros
and configure.ac file. DEBUG_CFLAGS has been once set in the build files
similarly to Zend.m4 but was then removed and simplified.

Also, this syncs phpize.m4 debug check with configure.ac so that #78788
is fixed there as well.
Related to: 0988f69

Author: petk

configure.ac

@@ -972,8 +972,6 @@ if test "$PHP_CONFIG_FILE_SCAN_DIR" = "DEFAULT"; then
 fi
 AC_MSG_RESULT([$PHP_CONFIG_FILE_SCAN_DIR])
 
-test -n "$DEBUG_CFLAGS" && CFLAGS="$CFLAGS $DEBUG_CFLAGS"
-
 PHP_ARG_ENABLE([sigchild],
   [whether to enable PHP's own SIGCHLD handler],
   [AS_HELP_STRING([--enable-sigchild],
@@ -1553,7 +1551,6 @@ PHP_SUBST(CPPFLAGS)
 PHP_SUBST(CXX)
 PHP_SUBST(CXXFLAGS)
 PHP_SUBST(CXXFLAGS_CLEAN)
-PHP_SUBST_OLD(DEBUG_CFLAGS)
 PHP_SUBST_OLD(EXTENSION_DIR)
 PHP_SUBST_OLD(EXTRA_LDFLAGS)
 PHP_SUBST_OLD(EXTRA_LDFLAGS_PROGRAM)

scripts/phpize.m4

@@ -116,8 +116,8 @@ if test "$PHP_DEBUG" = "yes"; then
   PHP_DEBUG=1
   ZEND_DEBUG=yes
   changequote({,})
-  CFLAGS=`echo "$CFLAGS" | $SED -e 's/-O[0-9s]*//g'`
-  CXXFLAGS=`echo "$CXXFLAGS" | $SED -e 's/-O[0-9s]*//g'`
+  CFLAGS=`echo "$CFLAGS" | "${SED}" -e 's/-O[0-9s]*//g'`
+  CXXFLAGS=`echo "$CXXFLAGS" | "${SED}" -e 's/-O[0-9s]*//g'`
   changequote([,])
   dnl Add -O0 only if GCC or ICC is used.
   if test "$GCC" = "yes" || test "$ICC" = "yes"; then