Fix building on musl libc.

src/client/linux/dump_writer_common/ucontext_reader.h

 // Copyright (c) 2014, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 32 matching lines @@
 struct UContextReader {
   static uintptr_t GetStackPointer(const struct ucontext* uc);
 
   static uintptr_t GetInstructionPointer(const struct ucontext* uc);
 
   // Juggle a arch-specific ucontext into a minidump format
   //   out: the minidump structure
   //   info: the collection of register structures.
 #if defined(__i386__) || defined(__x86_64)
   static void FillCPUContext(RawContextCPU *out, const ucontext *uc,
-                             const struct _libc_fpstate* fp);
+                             const struct _fpstate* fp);
 #elif defined(__aarch64__)
   static void FillCPUContext(RawContextCPU *out, const ucontext *uc,
                              const struct fpsimd_context* fpregs);
 #else
   static void FillCPUContext(RawContextCPU *out, const ucontext *uc);
 #endif
 };
 
 }  // namespace google_breakpad
 
 #endif  // CLIENT_LINUX_DUMP_WRITER_COMMON_UCONTEXT_READER_H