https://issues.dlang.org/show_bug.cgi?id=24268

          Issue ID: 24268
           Summary: Warning spam upon zlib C compilation
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody@puremagic.com
          Reporter: johanengelen@weka.io

When compiling zlib C source of Phobos (as part of DMD or LDC builds), there is
extreme warning spam like this:
```
D:\a\ldc\ldc\runtime\phobos\etc\c\zlib\gzlib.c(517,13): warning: a function
definition without a prototype is deprecated in all versions of C and is not
supported in C2x [-Wdeprecated-non-prototype]
int ZEXPORT gzeof(file)
```

We need to update all function definitions in the C source files...

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