Try to fix the Travis-CI build

Our previous travis build steps had a circular dependency between cmake and llvm:
we need to run cmake to update llvm to our picked revision, but we need to be on
our specific llvm revision in order to run cmake (newer LLVM's are incompatible
with our build scripts).

Break the dependency by manually calling git_svn_gotorev.py
Hopefully this syntax works

.travis.yml

@@ -16,8 +16,9 @@ install:
   - git config --global user.email "you@example.com"
   - git config --global user.name "Your Name"
   - mkdir ~/pyston-build && cd ~/pyston-build
+  - python ~/pyston/tools/git_svn_gotorev.py ~/pyston_deps/llvm-trunk `cat ~/pyston/llvm_revision.txt` ~/pyston/llvm_patches
+  - python ~/pyston/tools/git_svn_gotorev.py ~/pyston_deps/llvm-trunk/tools/clang `cat ~/pyston/llvm_revision.txt` ~/pyston/clang_patches
   - cmake -GNinja $TRAVIS_BUILD_DIR
-  - ninja llvm_up
   - ninja libunwind ext_cpython
 
 script: