fix pci_irq.c - memory leak - wrong irq_name allocated length (#367)

add function declaration to avoid compiling warning

add extra packages need for build

Co-authored-by: Yao Zhao <dragonlinux@gmail.com>

tools/build_gcc_toolchain.sh

@@ -89,7 +89,9 @@ case `cat /etc/os-release | grep '^NAME=' | cut -d'"' -f2` in
             wget
         ;;
     "Arch"*)
-        sudo pacman -S --needed --noconfirm gcc make flex wget texinfo libmpc gmp mpfr
+        sudo pacman -S --needed --noconfirm \
+            gcc make flex wget texinfo libmpc gmp mpfr \
+            diffutils pkgconf which unzip
         ;;
     *)
         ;;