Fix a compilation with non-clang/non-gcc compilers

patches/mutex.patch

 diff --git a/source/common/putilimp.h b/source/common/putilimp.h
-index e3da340..430e697 100644
+index e3da340..90bae92 100644
 --- a/source/common/putilimp.h
 +++ b/source/common/putilimp.h
 @@ -1,7 +1,7 @@
  /*
  ******************************************************************************
  *
 -*   Copyright (C) 1997-2014, International Business Machines
 +*   Copyright (C) 1997-2015, International Business Machines
  *   Corporation and others.  All Rights Reserved.
  *
  ******************************************************************************
-@@ -229,6 +229,23 @@ typedef size_t uintptr_t;
+@@ -229,6 +229,26 @@ typedef size_t uintptr_t;
  #endif
  
  
 +/**
 + *  \def U_HAVE_CLANG_ATOMICS
 + *  Defines whether Clang c11 style built-in atomics are avaialable.
 + *  These are used in preference to gcc atomics when both are available.
 + */
 +#ifdef U_HAVE_CLANG_ATOMICS
 +    /* Use the predefined value. */
-+#elif defined(__clang__) && \
-+      __has_builtin(__c11_atomic_load) && \
-+      __has_builtin(__c11_atomic_store) && \
-+      __has_builtin(__c11_atomic_fetch_add) && \
-+      __has_builtin(__c11_atomic_fetch_sub)
++#elif !defined(__clang__)
++#    define U_HAVE_CLANG_ATOMICS 0
++#else
++#if __has_builtin(__c11_atomic_load) && \
++    __has_builtin(__c11_atomic_store) && \
++    __has_builtin(__c11_atomic_fetch_add) && \
++    __has_builtin(__c11_atomic_fetch_sub)
 +#    define U_HAVE_CLANG_ATOMICS 1
 +#else
 +#    define U_HAVE_CLANG_ATOMICS 0
 +#endif
++#endif
 +
  /*===========================================================================*/
  /** @{ Code alignment                                                        */
  /*===========================================================================*/
 diff --git a/source/common/umutex.cpp b/source/common/umutex.cpp
 index 0c1fdc8..581f2b9 100644
 --- a/source/common/umutex.cpp
 +++ b/source/common/umutex.cpp
 @@ -349,8 +349,8 @@ umtx_atomic_dec(u_atomic_int32_t *p) {
  
@@ skipping 54 matching lines @@
 +
 +inline int32_t umtx_atomic_dec(u_atomic_int32_t *var) {
 +    return __c11_atomic_fetch_sub(var, 1, __ATOMIC_SEQ_CST) - 1;
 +}
 +U_NAMESPACE_END
 +
 +
  #elif U_HAVE_GCC_ATOMICS
  /*
   * gcc atomic ops. These are available on several other compilers as well.