mesa: guard better when building with sse4.1 optimisations

When the compiler is not capable/does not accept -msse4.1 while the target
has the instruction set we'll blow up as _mesa_streaming_load_memcpy is
going to be undefined.

To make sure that never happens, wrap the runtime cpu check+caller in an
ifdef thus do not compile that hunk of the code.

Fix the android build by enabling the optimisation and adding the define
where applicable.

v2: autoconf conditionals end with "fi" rather than endif.
v3: Wrap the definition and call to intel_miptree_{un,}map_movntdqa in
if defined(USE_SSE41). Spotted by Matt.

Cc: Matt Turner <mattst88@gmail.com>
Cc: Adrian Negreanu <adrian.m.negreanu@intel.com>
Cc: "10.1 10.2" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
diff --git a/configure.ac b/configure.ac
index 9aeebdf..4ff87eb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -235,6 +235,9 @@
 dnl Optional flags, check for compiler support
 dnl
 AX_CHECK_COMPILE_FLAG([-msse4.1], [SSE41_SUPPORTED=1], [SSE41_SUPPORTED=0])
+if test "x$SSE41_SUPPORTED" = x1; then
+    DEFINES="$DEFINES -DUSE_SSE41"
+fi
 AM_CONDITIONAL([SSE41_SUPPORTED], [test x$SSE41_SUPPORTED = x1])
 
 dnl