use `-std=c99`

I don't want GNU extensions, and using gnu99 was only temporary because
I didn't know how to enable POSIX standards, which this project relies
on.

1 files changed, 1 insertions, 1 deletions

diff --git a/build.sh b/build.sh
index 3ab36a8..049fb09 100755
--- a/build.sh
+++ b/build.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 cc=cc
-cflags=(-Wall -Wextra -std=gnu99 -O2)
+cflags=(-Wall -Wextra -std=c99 -D_XOPEN_SOURCE=700 -O2)
 ldflags=(-lm)
 
 platform=gl