android: fix gas-preprocessor download

An HTML page would be downloaded instead of the perl script. Also marks
said script as executable, else FFmpeg won't build.

Change-Id: I1a4521762e6fda49061f9d1e21ef81d5a88f3642

extras/tools/packages.mak

@@ -32,7 +32,7 @@ XZ_VERSION=5.2.2
 XZ_URL=http://tukaani.org/xz/xz-$(XZ_VERSION).tar.bz2
 
 GAS_VERSION=36bacb4cba27003c572e5bf7a9c4dfe3c9a8d40d
-GAS_URL=https://github.com/FFmpeg/gas-preprocessor/blob/$(GAS_VERSION)/gas-preprocessor.pl
+GAS_URL=https://raw.githubusercontent.com/FFmpeg/gas-preprocessor/$(GAS_VERSION)/gas-preprocessor.pl
 
 SED_VERSION=4.2.2
 SED_URL=$(GNU)/sed/sed-$(SED_VERSION).tar.bz2

extras/tools/tools.mak

@@ -216,7 +216,8 @@ gas-preprocessor-$(GAS_VERSION).pl:
 
 .gas: gas-preprocessor-$(GAS_VERSION).pl
 	mkdir -p $(PREFIX)/bin
-	cp gas-preprocessor-$(GAS_VERSION).pl $(PREFIX)/bin/gas-preprocessor
+	cp gas-preprocessor-$(GAS_VERSION).pl $(PREFIX)/bin/gas-preprocessor.pl
+	chmod a+x $(PREFIX)/bin/gas-preprocessor.pl # needs to be executable
 	touch $@
 
 CLEAN_FILE += .gas