Bump default build standard to gnu99

7 jobs for std_gnu99 in 16 minutes and 11 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Build
passed cross-android_api21_arm64 #194712

00:02:08

passed cross-android_api28_arm64 #194713

00:02:07

passed cross-mingw64 #194714

00:02:29

passed fedora-x86_64 #194711

00:05:31

passed msys2-mingw32 #194715
win32

00:08:14

passed vs2017-x64 #194716
win32

00:07:52

 
  Coverage
passed coverage #194717

00:02:21

74.1%