Enable pic (position independent code) config.

This is required on newer Debian-like systems and seems to be harmless
for older ones.

BUG=aomedia:102
BUG=aomedia:737

Change-Id: I44ec3f7f84447851b50d163839ddba171912e495

build/cmake/aom_config_defaults.cmake

@@ -76,7 +76,7 @@ set(CONFIG_LIBYUV 1 CACHE NUMBER "Enables libyuv scaling/conversion support.")
 set(CONFIG_MSVS 0 CACHE NUMBER "Building with MS Visual Studio (detected).")
 set(CONFIG_MULTITHREAD 1 CACHE NUMBER "Multithread support.")
 set(CONFIG_OS_SUPPORT 0 CACHE NUMBER "Internal flag.")
-set(CONFIG_PIC 0 CACHE NUMBER "Build with PIC enabled.")
+set(CONFIG_PIC 1 CACHE NUMBER "Build with PIC enabled.")
 set(CONFIG_RUNTIME_CPU_DETECT 1 CACHE NUMBER "Runtime CPU detection support.")
 set(CONFIG_SHARED 0 CACHE NUMBER "Build shared libs.")
 set(CONFIG_STATIC 1 CACHE NUMBER "Build static libs.")

configure

@@ -201,6 +201,7 @@ enable_feature spatial_resampling
 enable_feature multithread
 enable_feature os_support
 enable_feature highbitdepth
+enable_feature pic
 
 CODECS="
     av1_encoder