Expand PIC default to macho64 and respect CONFIG_PIC from libvpx

Change-Id: I8df65c6e52141183344ee91a7f94e8f4d5687e2f
diff --git a/third_party/x86inc/README.libvpx b/third_party/x86inc/README.libvpx
index c4fb568..d7d5bf2 100644
--- a/third_party/x86inc/README.libvpx
+++ b/third_party/x86inc/README.libvpx
@@ -12,3 +12,4 @@
 Prefix functions with vpx by default.
 Manage name mangling (prefixing with '_') manually because 'PREFIX' does not
   exist in libvpx.
+Expand PIC default to macho64 and respect CONFIG_PIC from libvpx
diff --git a/third_party/x86inc/x86inc.asm b/third_party/x86inc/x86inc.asm
index 3921895..229446f 100644
--- a/third_party/x86inc/x86inc.asm
+++ b/third_party/x86inc/x86inc.asm
@@ -96,11 +96,15 @@
 
 %if WIN64
     %define PIC
+%elifidn __OUTPUT_FORMAT__,macho64
+    %define PIC
 %elif ARCH_X86_64 == 0
 ; x86_32 doesn't require PIC.
 ; Some distros prefer shared objects to be PIC, but nothing breaks if
 ; the code contains a few textrels, so we'll skip that complexity.
     %undef PIC
+%elif CONFIG_PIC
+    %define PIC
 %endif
 %ifdef PIC
     default rel