Switch to sdl 1.2.15 and build from source on osx

Change-Id: I036eefd9789bfe346e9ee5acc15c1d9ffe995c94
diff --git a/INSTALL b/INSTALL
index 989b714..c9d178a 100644
--- a/INSTALL
+++ b/INSTALL
@@ -77,7 +77,7 @@
   1/ First, build Android's patched libSDL as a static library,
      this can be done as:
 
-        cd $TOP/external/qemu/distrib/sdl-1.2.12
+        cd $TOP/external/qemu/distrib/sdl-1.2.15
         ./android-configure --prefix=<PATH>
         make
         make install
diff --git a/Makefile.common b/Makefile.common
index 4382bd2..51fcb85 100644
--- a/Makefile.common
+++ b/Makefile.common
@@ -198,14 +198,6 @@
     BUILD_SDL_FROM_SOURCES := false
 endif
 
-# On darwin-x86, a bug in the Android build system prevents the compilation
-# of Objective-C sources. Fixed recently in AOSP, but we still use the
-# prebuilts for the benefit of older platform branches.
-#
-ifeq ($(QEMU_HOST_TAG),darwin-x86)
-    BUILD_SDL_FROM_SOURCES := false
-endif
-
 # If we're building with android-configure.sh && make, always build from
 # sources to catch regressions as soon as they happen.
 #
@@ -238,7 +230,7 @@
 
 else # BUILD_SDL_FROM_SOURCES
 
-    SDL_DIR := distrib/sdl-1.2.12
+    SDL_DIR := distrib/sdl-1.2.15
     include $(LOCAL_PATH)/$(SDL_DIR)/sources.make
     common_LOCAL_SRC_FILES += $(SDL_SOURCES)
 
diff --git a/distrib/README b/distrib/README
index 8a2cf52..22d276f 100644
--- a/distrib/README
+++ b/distrib/README
@@ -39,12 +39,4 @@
     "dynamic ticks" that make this mode un-necessary for Android.
 
 
-it also uses a patched version of LibSDL-1.2.12 which implements the following:
-
-  - prevent a fatal bug in Quartz Extreme's QuickDraw emulation to crash the program
-    whenever SDL_WINDOW_POS is set in the environment before starting the program.
-    the patch implements a simple workaround to this system-level problem.
-
-  - new APIs: SDL_WM_GetPos() and SDL_WM_SetPos() are used to retrieve and set the emulator
-    window position. this allows us to implement a simple-yet-useful feature: the emulator remembers
-    its position among restarts.
+it also uses a patched version of LibSDL-1.2.15.