build: fix compiler version detection

Compiler version tuples should be numeric for tuple comparisons
to work.

Also correct check for AIX where the minimum supported GCC is 6.3.0

PR-URL: #24879
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

configure.py

@@ -655,8 +655,8 @@ def try_check_compiler(cc, lang):
 
   values = (proc.communicate()[0].split() + ['0'] * 7)[0:7]
   is_clang = values[0] == '1'
-  gcc_version = tuple(values[1:1+3])
-  clang_version = tuple(values[4:4+3])
+  gcc_version = tuple(map(int, values[1:1+3]))
+  clang_version = tuple(map(int, values[4:4+3])) if is_clang else None
 
   return (True, is_clang, clang_version, gcc_version)
 
@@ -753,6 +753,8 @@ def check_compiler(o):
   ok, is_clang, clang_version, gcc_version = try_check_compiler(CXX, 'c++')
   if not ok:
     warn('failed to autodetect C++ compiler version (CXX=%s)' % CXX)
+  elif sys.platform.startswith('aix') and gcc_version < (6, 3, 0):
+    warn('C++ compiler too old, need g++ 6.3.0 (CXX=%s)' % CXX)
   elif clang_version < (3, 4, 2) if is_clang else gcc_version < (4, 9, 4):
     warn('C++ compiler too old, need g++ 4.9.4 or clang++ 3.4.2 (CXX=%s)' % CXX)
 
@@ -921,8 +923,7 @@ def gcc_version_ge(version_checked):
   for compiler in [(CC, 'c'), (CXX, 'c++')]:
     ok, is_clang, clang_version, compiler_version = \
       try_check_compiler(compiler[0], compiler[1])
-    compiler_version_num = tuple(map(int, compiler_version))
-    if is_clang or compiler_version_num < version_checked:
+    if is_clang or compiler_version < version_checked:
       return False
   return True