Summary:
X-link: https://github.com/facebook/react-native/pull/39051
Pull Request resolved: https://github.com/facebook/yoga/pull/1344
`YGJNILogFunc` has a bug where it uses a `va_list` to determine the length of a printf string, then reuses the same `va_list` later after it has already been iterated through. Even if no arguments are present, this may cause a crash looking something like:
```
C [libsystem_platform.dylib+0xf12] _platform_strlen+0x12
C [libsystem_c.dylib+0x31bf] __vfprintf+0x1339
C [libsystem_c.dylib+0x307ce] _vsnprintf+0x100
C [libsystem_c.dylib+0x6965] vsnprintf+0x44
C [libyoga.dylib+0x5161] YGJNILogFunc(YGConfig*, YGNode*, YGLogLevel, void*, char const*, __va_list_tag*)+0x59
```
Fixing this fixes crashing unit tests which are not explicitly disabled.
Reviewed By: yungsters
Differential Revision: D48388548
fbshipit-source-id: 492e7a89aeb5f9d15485ce31641875a295356bef
38ad93c87b