allow shell rs_exec:file rx_file_perms

Hostside tests depend on being able to execute /system/bin/bcc. Allow
it.

From bug:

In the NDK:

  $ ./checkbuild.py
  $ virtualenv -p ../out/bootstrap/bin/python3 env
  $ source env/bin/activate
  $ ./run_tests.py --filter rs-cpp-basic
  FAIL rs-cpp-basic.rstest-compute [armeabi-v7a-19]: android-28 marlin HT67L0200247 QPP1.190205.017
  New RS 0xee70f000
  Segmentation fault

  FAIL rs-cpp-basic.rstest-compute [arm64-v8a-21]: android-28 marlin HT67L0200247 QPP1.190205.017
  New RS 0x7a91e13000
  Segmentation fault

  02-23 23:00:45.635  9516  9518 V RenderScript: Successfully loaded runtime: libRSDriver_adreno.so
  02-23 23:00:45.650  9518  9518 W rstest-compute: type=1400 audit(0.0:15): avc: denied { read } for name="bcc" dev="dm-0" ino=390 scontext=u:r:shell:s0 tcontext=u:object_r:rs_exec:s0 tclass=file permissive=0
  02-23 23:00:45.651  9516  9518 E RenderScript: Cannot open file '/system/bin/bcc' to compute checksum
  02-23 23:00:45.652  9516  9516 E rsC++   : Internal error: Object id 0.

Test: compiles
Fixes: 126388046
Change-Id: I28e591d660c4ba9a33135e940d298d35474ef0b6
diff --git a/private/shell.te b/private/shell.te
index 9bfac6c..0d1cf03 100644
--- a/private/shell.te
+++ b/private/shell.te
@@ -66,3 +66,7 @@
 # The dl.exec_linker* tests need to execute /system/bin/linker
 # b/124789393
 allow shell system_linker_exec:file rx_file_perms;
+
+# Renderscript host side tests depend on being able to execute
+# /system/bin/bcc (b/126388046)
+allow shell rs_exec:file rx_file_perms;