Get some symbols from libgcc so it works on nightly (#58)

* Use the same logic from aarch64 apple on x86

Author: gbaraldi

src/Quadmath.jl

@@ -22,7 +22,7 @@ import Base: (*), +, -, /,  <, <=, ==, ^, convert,
 using Random
 
 if Sys.isapple() && Sys.ARCH == :x86_64
-    const quadoplib = "libquadmath.0"
+    const quadoplib = "libgcc_s.1.dylib"
     const libquadmath = "libquadmath.0"
 elseif Sys.isapple() && Sys.ARCH == :aarch64
     const quadoplib = "libgcc_s.1.1.dylib"