Remove duplicate PT_ARM_EXIDX definition.

Change-Id: I62aefc53c3f24254ca193d29c80050ed20a671bf
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index 49c3b57..ef7671c 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -1280,11 +1280,6 @@
 
 
 #if defined(__arm__)
-
-#  ifndef PT_ARM_EXIDX
-#    define PT_ARM_EXIDX    0x70000001      /* .ARM.exidx segment */
-#  endif
-
 /* Return the address and size of the .ARM.exidx section in memory,
  * if present.
  *