setup.py: fix build with gcc 4.8

Fix the following build failure on gcc 4.8 which is raised since version
2.0.0 and
9084152:

vendor/hiredis/read.c: In function 'redisReaderFree':
vendor/hiredis/read.c:646:9: error: 'for' loop initial declarations are only allowed in C99 mode
         for (int i = 0; i < r->tasks; i++) {
         ^
vendor/hiredis/read.c:646:9: note: use option -std=c99 or -std=gnu99 to compile your code

This build failure is raised because hiredis source code is built
without C99:
redis/hiredis@13a35bd

Fixes:
 - http://autobuild.buildroot.org/results/04cbcddf6d83ebad8c98400754f9445375e9e489

Signed-off-by: Fabrice Fontaine <[email protected]>

Author: ffontaine

setup.py

@@ -13,6 +13,7 @@ def version():
 ext = Extension("hiredis.hiredis",
   sources=sorted(glob.glob("src/*.c") +
                  ["vendor/hiredis/%s.c" % src for src in ("alloc", "read", "sds")]),
+  extra_compile_args=["-std=c99"],
   include_dirs=["vendor"])
 
 setup(