Added test for ifunc support in dynamic linker.

ifuncs now work in i386 and x86_64 when called in the same library as
well as in a different library.

Bug:6657325
(cherry picked from commit c5a13efa9bc4264be0a9a9e37c00633af01584ed)

Change-Id: I321d780bc2f9bd1baa749e1acacd2683aefe827b
diff --git a/libc/include/elf.h b/libc/include/elf.h
index 0975b7a..faae73e 100644
--- a/libc/include/elf.h
+++ b/libc/include/elf.h
@@ -69,14 +69,17 @@
 
 #define PT_GNU_RELRO 0x6474e552
 
-#define STB_LOOS   10
-#define STB_HIOS   12
-#define STB_LOPROC 13
-#define STB_HIPROC 15
+#define STB_LOOS      10
+#define STB_HIOS      12
+#define STB_LOPROC    13
+#define STB_HIPROC    15
 
-#define STT_LOOS   10
-#define STT_HIOS   12
-#define STT_LOPROC 13
-#define STT_HIPROC 15
+#define STT_GNU_IFUNC 10
+#define STT_LOOS      10
+#define STT_HIOS      12
+#define STT_LOPROC    13
+#define STT_HIPROC    15
+
+#define R_386_IRELATIVE  42
 
 #endif /* _ELF_H */