[PATCH] [libc++] Support Newlib as libc++'s C library [cmath part, part 2]

[Jonathan Roelofs]

================
Comment at: include/support/newlib/math.h:26
@@ +25,3 @@
+inline _LIBCPP_INLINE_VISIBILITY long double logbl(long double __x) _NOEXCEPT {
+    return __builtin_logb(__x);
+}
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Should be taken care of here: https://sourceware.org/ml/newlib/2014/msg00469.html

http://reviews.llvm.org/D5420