[Issue 23622] ImportC fails to compile files which include math.h

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23622

--- Comment #2 from Walter Bright <bugzilla at digitalmars.com> ---
A reduced test case:

  enum {  FP_NAN = 0 };
  #define FP_NAN 0

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