[CircleCI] cache Halide headers properly

Ever since the first deployment of CircleCI caching for Halide in the
prehistory, caching was misconfigured and Halide was recompiled on every
test run.  Contrary to other buildable dependences, Halide does not
create a directory for include files like
"third-party-install/include/Halide/" but installs headers directly into
"third-party-install/Halide".  The cache was configured to store this
non-existent directory, failing to capture header files and this
triggering re-compilation and re-installation on every run.  Explicitly
list all Halide headers to store in the cache.  Note that the CI
configuration will have to be updated if Halide header names change.
A better solution would be to make Halide install its headers in a
subdirectory, but would require changing Halide's makefile.

Author: ftynse

.circleci/config.yml

@@ -94,7 +94,16 @@ jobs:
       - save_cache:
           key: v1-halide-{{ checksum ".git/modules/third-party/halide/HEAD" }}-{{ checksum "build.sh" }}-{{ checksum ".circleci/config.yml" }}-{{ arch }}-1404
           paths:
-            - third-party-install/include/Halide
+            - third-party-install/include/HalideBuffer.h
+            - third-party-install/include/Halide.h
+            - third-party-install/include/HalideRuntimeCuda.h
+            - third-party-install/include/HalideRuntime.h
+            - third-party-install/include/HalideRuntimeHexagonHost.h
+            - third-party-install/include/HalideRuntimeMetal.h
+            - third-party-install/include/HalideRuntimeOpenCL.h
+            - third-party-install/include/HalideRuntimeOpenGLCompute.h
+            - third-party-install/include/HalideRuntimeOpenGL.h
+            - third-party-install/include/HalideRuntimeQurt.h
             - third-party-install/lib/libHalide.so
             - third-party-install/lib/libHalide.a
 
@@ -204,7 +213,16 @@ jobs:
       - save_cache:
           key: v1-halide-{{ checksum ".git/modules/third-party/halide/HEAD" }}-{{ checksum "build.sh" }}-{{ checksum ".circleci/config.yml" }}-{{ arch }}-1604
           paths:
-            - third-party-install/include/Halide
+            - third-party-install/include/HalideBuffer.h
+            - third-party-install/include/Halide.h
+            - third-party-install/include/HalideRuntimeCuda.h
+            - third-party-install/include/HalideRuntime.h
+            - third-party-install/include/HalideRuntimeHexagonHost.h
+            - third-party-install/include/HalideRuntimeMetal.h
+            - third-party-install/include/HalideRuntimeOpenCL.h
+            - third-party-install/include/HalideRuntimeOpenGLCompute.h
+            - third-party-install/include/HalideRuntimeOpenGL.h
+            - third-party-install/include/HalideRuntimeQurt.h
             - third-party-install/lib/libHalide.so
             - third-party-install/lib/libHalide.a