Add CONFIG_SRAM to allow use of on-chip SRAM on some systems

Some SoCs have a small amount of on-chip SRAM which may be used
for frequently used code or data.  When enabled, this option
will allow FFmpeg to use such facilities where supported.

Originally committed as revision 21564 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -232,6 +232,7 @@ Advanced options (experts only):
   --disable-yasm           disable use of yasm assembler
   --enable-pic             build position-independent code
   --malloc-prefix=PFX      prefix malloc and related names with PFX
+  --enable-sram            allow use of on-chip SRAM
 
 Developer options (useful when working on FFmpeg itself):
   --disable-debug          disable debugging symbols
@@ -915,6 +916,7 @@ CONFIG_LIST="
     runtime_cpudetect
     shared
     small
+    sram
     static
     swscale
     swscale_alpha