Resolve several travis-ci issues

MBEDTLS_VERSION, OPENSSL_VERSION were defined twice - in both
.travis.yml and .travis/build-deps.sh files, the last one
defined OPENSSL_VERSION via nonexistent OPENSSL_VERION variable, which lead us to use openssl-1.0.1 instead of openssl-1.0.2, I removed variable definition from build-deps.sh

"cache: [ apt: true ]" is not a travis supported option, it was introduced by mistake, I removed it

LD_LIBRARY_PATH was defined for the entire test run, it includes custom openssl build, which was picked by "wget", so "wget" could not verify SSL cert at https://www.openssl.org sometimes. We do not want wget to pick our custom LD_LIBRARY_PATH, so I moved that variable to "script" section

LD_LIBRARY_PATH was defined for both linux and osx environments, for the second DYLD_LIBRARY_PATH must be defined instead

v2: Upgrade openssl, mbedtls to the most recent versions

---
 .travis.yml           | 7 +++----
 .travis/build-deps.sh | 2 --
 2 files changed, 3 insertions(+), 6 deletions(-)

.travis.yml +3 -4

index 369db97..dd340f5 100644
@@ -12,13 +12,12 @@ env:
   global:
     - JOBS=3
     - PREFIX="${HOME}/opt"
-    - MBEDTLS_VERSION="2.2.1"
+    - MBEDTLS_VERSION="2.4.0"
     - MBEDTLS_CFLAGS="-I${PREFIX}/include"
     - MBEDTLS_LIBS="-L${PREFIX}/lib -lmbedtls -lmbedx509 -lmbedcrypto"
-    - OPENSSL_VERSION="1.0.1t"
+    - OPENSSL_VERSION="1.0.2k"
     - OPENSSL_CFLAGS="-I${PREFIX}/include"
     - OPENSSL_LIBS="-L${PREFIX}/lib -lssl -lcrypto"
-    - LD_LIBRARY_PATH="${PREFIX}/lib:${LD_LIBRARY_PATH}"
 
 matrix:
   include:

@@ -63,7 +62,6 @@ addons:
       - linux-libc-dev
 
 cache:
-  apt: true
   ccache: true
   directories:
   - download-cache

@@ -77,6 +75,7 @@ install:
   - .travis/build-deps.sh > build-deps.log 2>&1 || (cat build-deps.log &&
 exit 1)
 
 script:
+  - export LD_LIBRARY_PATH="${PREFIX}/lib:${LD_LIBRARY_PATH}"
   - autoreconf -vi
   - ./configure --with-crypto-library="${SSLLIB}" ${EXTRA_CONFIG} ||

(cat config.log && exit 1)
- make -j$JOBS

.travis/build-deps.sh +0 -3

index bda54ee..3ffba0b 100755
@@ -2,8 +2,6 @@
 set -eux
 
 # Set defaults
-MBEDTLS_VERSION="${MBEDTLS_VERSION:-2.2.1}"
-OPENSSL_VERSION="${OPENSSL_VERION:-1.0.2h}"
 PREFIX="${PREFIX:-${HOME}/opt}"
 
 download_mbedtls () {
--

2.5.5