Scripts and tools: increased timeout downloading

DOWNLOAD_CONNECT_TIMEOUT changed from 10 to 30 because some file start only after 15 sec (see below).

Fetching boost_1_64_0.tar.bz2 from https://dl.bintray.com/boostorg/release/1.64.0/source/
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:--  0:00:15 --:--:--     0
100 76.7M  100 76.7M    0     0  1863k      0  0:00:42  0:00:42 --:--:-- 8136k
/home/gitianuser/bitcoin/depends/work/download/boost-1_64_0/boost_1_64_0.tar.bz2.temp: OK

depends/Makefile

@@ -15,7 +15,7 @@ HOST ?= $(BUILD)
 PATCHES_PATH = $(BASEDIR)/patches
 BASEDIR = $(CURDIR)
 HASH_LENGTH:=11
-DOWNLOAD_CONNECT_TIMEOUT:=10
+DOWNLOAD_CONNECT_TIMEOUT:=30
 DOWNLOAD_RETRIES:=3
 HOST_ID_SALT ?= salt
 BUILD_ID_SALT ?= salt