configure: Fix errors with AST_UNDEFINED_SANITIZER/AST_LEAK_SANITIZER

When running on a system that does not support or use AST_UNDEFINED_SANITIZER
or AST_LEAK_SANITIZER, the configure script would incorrectly set those
constants to a blank value, e.g., 'AST_UNDEFINED_SANITIZER='. This would
cause menuselect to error out, complaining that a blank value is not a
valid option. This patch corrects the issue by setting the value to 0 if
the options that those constants enable/disable is not found.

Change-Id: Ib39814aaf940f308d500c1e026edb3d70de47fba

configure

@@ -13772,7 +13772,7 @@ else
     We can't simply define LARGE_OFF_T to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
+#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
   int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
 		       && LARGE_OFF_T % 2147483647 == 1)
 		      ? 1 : -1];
@@ -13818,7 +13818,7 @@ else
     We can't simply define LARGE_OFF_T to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
+#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
   int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
 		       && LARGE_OFF_T % 2147483647 == 1)
 		      ? 1 : -1];
@@ -13842,7 +13842,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
     We can't simply define LARGE_OFF_T to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
+#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
   int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
 		       && LARGE_OFF_T % 2147483647 == 1)
 		      ? 1 : -1];
@@ -13887,7 +13887,7 @@ else
     We can't simply define LARGE_OFF_T to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
+#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
   int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
 		       && LARGE_OFF_T % 2147483647 == 1)
 		      ? 1 : -1];
@@ -13911,7 +13911,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
     We can't simply define LARGE_OFF_T to be 9223372036854775807,
     since some C++ compilers masquerading as C compilers
     incorrectly reject 9223372036854775807.  */
-#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
+#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
   int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
 		       && LARGE_OFF_T % 2147483647 == 1)
 		      ? 1 : -1];
@@ -17774,7 +17774,7 @@ if ac_fn_c_try_compile "$LINENO"; then :
 $as_echo "yes" >&6; }
 	AST_LEAK_SANITIZER=1
 else
-  AST_LEAK_SANITIZER=
+  AST_LEAK_SANITIZER=0
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 
@@ -17806,7 +17806,7 @@ if ac_fn_c_try_compile "$LINENO"; then :
 $as_echo "yes" >&6; }
 	AST_UNDEFINED_SANITIZER=1
 else
-  AST_UNDEFINED_SANITIZER=
+  AST_UNDEFINED_SANITIZER=0
 	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
 $as_echo "no" >&6; }
 

configure.ac

@@ -1117,7 +1117,7 @@ AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM([], [int x = 1;])],
 	AC_MSG_RESULT(yes)
 	[AST_LEAK_SANITIZER=1],
-	[AST_LEAK_SANITIZER=]
+	[AST_LEAK_SANITIZER=0]
 	AC_MSG_RESULT(no)
 )
 CFLAGS="${saved_sanitize_CFLAGS}"
@@ -1133,7 +1133,7 @@ AC_COMPILE_IFELSE(
 	[AC_LANG_PROGRAM([], [int x = 1;])],
 	AC_MSG_RESULT(yes)
 	[AST_UNDEFINED_SANITIZER=1],
-	[AST_UNDEFINED_SANITIZER=]
+	[AST_UNDEFINED_SANITIZER=0]
 	AC_MSG_RESULT(no)
 )
 CFLAGS="${saved_sanitize_CFLAGS}"