Test adding symbols in build.rs

Author: tgross35

build.rs

@@ -477,6 +477,10 @@ mod c {
                 ("__floatunsitf", "floatunsitf.c"),
                 ("__trunctfdf2", "trunctfdf2.c"),
                 ("__trunctfsf2", "trunctfsf2.c"),
+                ("__addtf3", "addtf3.c"),
+                ("__multf3", "multf3.c"),
+                ("__subtf3", "subtf3.c"),
+                ("__divtf3", "divtf3.c"),
                 ("__powitf2", "powitf2.c"),
                 ("__fe_getround", "fp_mode.c"),
                 ("__fe_raise_inexact", "fp_mode.c"),