Replace Schema.s with generated .cpp file

This removes the dependency on an assembler (which must support .incbin).
Instead we use xxd as a custom build command to generate a .cpp file
which is included in the build.

This makes it possible to build on Windows, for which you need 
cp.exe (from GNU Core Utils) and xxd.exe (from Vim).

Change-Id: I3a929640b1fdbfc27e2c38abd05bf3a298245ba5
Signed-off-by: Robert Hughes <robert.hughes@arm.com>
diff --git a/src/armnnTfLiteParser/test/ParserFlatbuffersFixture.hpp b/src/armnnTfLiteParser/test/ParserFlatbuffersFixture.hpp
index acca01b..797e11e 100644
--- a/src/armnnTfLiteParser/test/ParserFlatbuffersFixture.hpp
+++ b/src/armnnTfLiteParser/test/ParserFlatbuffersFixture.hpp
@@ -101,7 +101,7 @@
 
     bool ReadStringToBinary()
     {
-        std::string schemafile(&tflite_schema_start, &tflite_schema_end);
+        std::string schemafile(g_TfLiteSchemaText, g_TfLiteSchemaText + g_TfLiteSchemaText_len);
 
         // parse schema first, so we can use it to parse the data after
         flatbuffers::Parser parser;