Move core and runtime files to a single library

Now core and runtime files are build in the same library,
libarm_compute.so and libarm_compute-static.a. Create a dummy
core library for not breaking backwards compatibility.

Update documentation on fat binaries and new high priority
library.

Fixed issue on scons when using the install_dir feature.

Change-Id: I5a8a6bbe2808243eba07fd135496995259d8702f
Signed-off-by: Michalis Spyrou <michalis.spyrou@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/5845
Tested-by: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>
diff --git a/SConstruct b/SConstruct
index db6e3e0..8fa78b4 100644
--- a/SConstruct
+++ b/SConstruct
@@ -65,6 +65,7 @@
     PathVariable("build_dir", "Specify sub-folder for the build", ".", PathVariable.PathAccept),
     PathVariable("install_dir", "Specify sub-folder for the install", "", PathVariable.PathAccept),
     BoolVariable("exceptions", "Enable/disable C++ exception support", True),
+    BoolVariable("high_priority", "Generate a library containing only the high priority operators", False),
     PathVariable("linker_script", "Use an external linker script", "", PathVariable.PathAccept),
     PathVariable("external_tests_dir", "Add examples, benchmarks and tests to the tests suite", "", PathVariable.PathAccept),
     ListVariable("custom_options", "Custom options that can be used to turn on/off features", "none", ["disable_mmla_fp"]),