[lldb] Use the build's python interpreter in the shell tests

Make sure that the shell tests use the same python interpreter as the
rest of the build instead of picking up `python` from the PATH.

It would be nice if we could use the _disallow helper, but that triggers
on invocations that specify python as the scripting language.

lldb/test/Shell/ScriptInterpreter/Python/Crashlog/json.test

@@ -1,11 +1,11 @@
 # RUN: %clang_host -g %S/Inputs/test.c -o %t.out
 
 # RUN: cp %S/Inputs/a.out.ips %t.crash
-# RUN: python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}' --json
+# RUN: %python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}' --json
 # RUN: %lldb %t.out -o 'command script import lldb.macosx.crashlog' -o 'crashlog %t.crash' 2>&1 | FileCheck %s
 
 # RUN: cp %S/Inputs/a.out.ips %t.nometadata.crash
-# RUN: python %S/patch-crashlog.py --binary %t.out --crashlog %t.nometadata.crash --offsets '{"main":20, "bar":9, "foo":16}' --json --no-metadata
+# RUN: %python %S/patch-crashlog.py --binary %t.out --crashlog %t.nometadata.crash --offsets '{"main":20, "bar":9, "foo":16}' --json --no-metadata
 # RUN: %lldb %t.out -o 'command script import lldb.macosx.crashlog' -o 'crashlog %t.nometadata.crash' 2>&1 | FileCheck %s
 
 # CHECK: Thread[0] Crashing Thread Name EXC_BAD_ACCESS (SIGSEGV) (KERN_INVALID_ADDRESS at 0x0000000000000000)

lldb/test/Shell/ScriptInterpreter/Python/Crashlog/no_threadState.test

@@ -1,7 +1,7 @@
 # RUN: %clang_host -g %S/Inputs/test.c -o %t.out
 
 # RUN: cp %S/Inputs/no_threadState.ips %t.crash
-# RUN: python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}' --json
+# RUN: %python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}' --json
 # RUN: %lldb %t.out -o 'command script import lldb.macosx.crashlog' -o 'crashlog %t.crash' 2>&1 | FileCheck %s
 
 # CHECK: Thread[0] Crashing Thread Name EXC_BAD_ACCESS (SIGSEGV) (KERN_INVALID_ADDRESS at 0x0000000000000000)

lldb/test/Shell/ScriptInterpreter/Python/Crashlog/text.test

@@ -1,6 +1,6 @@
 # RUN: %clang_host -g %S/Inputs/test.c -o %t.out
 # RUN: cp %S/Inputs/a.out.crash %t.crash
-# RUN: python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}'
+# RUN: %python %S/patch-crashlog.py --binary %t.out --crashlog %t.crash --offsets '{"main":20, "bar":9, "foo":16}'
 # RUN: %lldb %t.out -o 'command script import lldb.macosx.crashlog' -o 'crashlog %t.crash' 2>&1 | FileCheck %s
 
 # CHECK: Thread[0] EXC_BAD_ACCESS (SIGSEGV) (KERN_INVALID_ADDRESS at 0x0000000000000000)