Use conda compiler toolchain for conda builds

For both libastra and astra-toolbox:

1) We do not use script_env to set CC/CXX anymore, since the compilers
   are installed by conda.
2) The build string is made useful by including either the python+numpy
   version or the cudatoolkit version that the package was built with.
3) Some clean-up of build.sh in buildenv/

For libastra:

1) The libastra.so is built with the conda C/C++ compiler
   toolchain. This has two benefits:
   1) The rpath of libastra.so is set to $ORIGIN, which makes linking
      easier for dependent packages.
   2) libastra.so is linkable against ancient versions of glibc. With
      old versions of memcpy.
2) The C/C++ compiler version is fixed to 5.4.0
3) In libastra/build.sh, we rename $CONDA_PREFIX to
   $PREFIX. Apparently, this is how it is supposed to be done. For me,
   $CONDA_PREFIX was suddenly undefined. Why this was not a problem
   before, is unclear to me.
4) The cudatoolkit runtime dependency is pinned with pin_compatible
5) The libastra conda package now provides headers and .pc file. This
   is useful for building C++ packages that depend on astra.
6) Remove some old code related to cudatoolkit<8.0.

For astra-toolbox:

1) astra-toolbox uses the conda-provided compilers
2) The compilers are fixed to version 7.3
3) Add boost to host requirements of astra-toolbox

Notes on testing:

- The libastra build has been tested with all versions of cudatoolkit
- The astra-toolbox build has been tested with all provided versions
  of python after building a single cudatoolkit version of libastra.

How to test this branch:

- It should work by just editing
  `python/conda/linux_release/buildenv/build.sh`. Set
  BRANCH=CI-use-conda-c-compiler-toolchain
  URL=https://github.com/ahendriksen/astra-toolbox

  and run release.sh from the `python/conda/linux_release` directory.

5 files changed, 22 insertions, 3 deletions

diff --git a/python/conda/astra-toolbox/conda_build_config_py27.yaml b/python/conda/astra-toolbox/conda_build_config_py27.yaml
index f119b61..869d22e 100644
--- a/python/conda/astra-toolbox/conda_build_config_py27.yaml
+++ b/python/conda/astra-toolbox/conda_build_config_py27.yaml
@@ -8,3 +8,8 @@ numpy:
   - 1.14
   - 1.15
   - 1.16
+
+c_compiler_version:
+  - 7.3
+cxx_compiler_version:
+  - 7.3
diff --git a/python/conda/astra-toolbox/conda_build_config_py35.yaml b/python/conda/astra-toolbox/conda_build_config_py35.yaml
index 8dd963c..72d4cef 100644
--- a/python/conda/astra-toolbox/conda_build_config_py35.yaml
+++ b/python/conda/astra-toolbox/conda_build_config_py35.yaml
@@ -3,3 +3,7 @@ python:
 
 numpy:
   - 1.15
+c_compiler_version:
+  - 7.3
+cxx_compiler_version:
+  - 7.3
diff --git a/python/conda/astra-toolbox/conda_build_config_py36.yaml b/python/conda/astra-toolbox/conda_build_config_py36.yaml
index f043435..996e22c 100644
--- a/python/conda/astra-toolbox/conda_build_config_py36.yaml
+++ b/python/conda/astra-toolbox/conda_build_config_py36.yaml
@@ -5,3 +5,7 @@ numpy:
   - 1.14
   - 1.15
   - 1.16
+c_compiler_version:
+  - 7.3
+cxx_compiler_version:
+  - 7.3
diff --git a/python/conda/astra-toolbox/conda_build_config_py37.yaml b/python/conda/astra-toolbox/conda_build_config_py37.yaml
index ebbf44a..4282407 100644
--- a/python/conda/astra-toolbox/conda_build_config_py37.yaml
+++ b/python/conda/astra-toolbox/conda_build_config_py37.yaml
@@ -6,3 +6,7 @@ numpy:
   - 1.14
   - 1.15
   - 1.16
+c_compiler_version:
+  - 7.3
+cxx_compiler_version:
+  - 7.3
diff --git a/python/conda/astra-toolbox/meta.yaml b/python/conda/astra-toolbox/meta.yaml
index 054751b..b3c036b 100644
--- a/python/conda/astra-toolbox/meta.yaml
+++ b/python/conda/astra-toolbox/meta.yaml
@@ -8,8 +8,7 @@ source:
 
 build:
   number: 0
-  script_env:
-    - CC # [linux]
+  string: py_{{ python }}_numpy_{{ numpy }}
 
 test:
   imports:
@@ -24,14 +23,17 @@ test:
 
 requirements:
   build:
+    - {{ compiler('c') }}    # [win or linux]
+    - {{ compiler('cxx') }}  # [linux]
+  host:
     - python
     - cython >=0.13
+    - boost # [osx or linux]
     - nomkl # [not win]
     - numpy {{ numpy }}
     - scipy
     - six
     - libastra ==1.9.0.dev11
-
   run:
     - python
     - {{ pin_compatible('numpy', min_pin='x.x', max_pin='x.x') }}