[PATCH] gdb: Fix build error on macOS

[Enze Li <lienze2010@hotmail.com>]

PR build/28413 notes that the gdb master fails to build on macOS.

Based on De Morgan's law, the expression
!(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
is equal to (!defined __GNUC__ || defined __clang__ || !__OPTIMIZE).
The expression above looks weird, maybe there are some problems with
this way of judging. When any one of the conditions is established, the
subsequent judgment will be ignored.

This patch works around the issue by rewriting the expression of
judgment after referring to the nearby notes.

Tested by building on x86_64-Linux and macOS(Mojave & Catalina).

Bug: https://sourceware.org/PR28413
---
 gnulib/import/c++defs.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gnulib/import/c++defs.h b/gnulib/import/c++defs.h
index 39df1bc76bc..dbbae2f1fa2 100644
--- a/gnulib/import/c++defs.h
+++ b/gnulib/import/c++defs.h
@@ -286,7 +286,7 @@
    _GL_CXXALIASWARN_2 (func, namespace)
 /* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
    we enable the warning only when not optimizing.  */
-# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
+# if defined __GNUC__ && !defined __clang__ && !__OPTIMIZE__
 #  define _GL_CXXALIASWARN_2(func,namespace) \
     _GL_WARN_ON_USE (func, \
                      "The symbol ::" #func " refers to the system function. " \
@@ -314,7 +314,7 @@
    _GL_CXXALIASWARN1_2 (func, rettype, parameters_and_attributes, namespace)
 /* To work around GCC bug <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43881>,
    we enable the warning only when not optimizing.  */
-# if !(defined __GNUC__ && !defined __clang__ && __OPTIMIZE__)
+# if defined __GNUC__ && !defined __clang__ && !__OPTIMIZE__
 #  define _GL_CXXALIASWARN1_2(func,rettype,parameters_and_attributes,namespace) \
     _GL_WARN_ON_USE_CXX (func, rettype, rettype, parameters_and_attributes, \
                          "The symbol ::" #func " refers to the system function. " \
-- 
2.30.2