Ignore downloaded files and generated code dir (#610)

Author: sbellem

.gitignore

@@ -17,3 +17,18 @@
 #output files
 /build/
 /linux/installer/bin/*.bin
+
+# files downloaded in preparation phase
+Intel redistributable binary.txt
+Master_EULA_for_Intel_Sw_Development_Products.pdf
+external/ippcp_internal/inc/ippcp.h
+external/ippcp_internal/inc/ippcpdefs.h
+external/ippcp_internal/inc/ippversion.h
+external/ippcp_internal/inc/sgx_ippcp.h
+external/ippcp_internal/license/
+external/toolset/
+psw/ae/data/prebuilt/README.md
+redist.txt
+
+# directory created when running reproducibility scripts
+linux/reproducibility/code_dir/