Reapply "[TSan] Make Test work with Internal Shell"

This reverts commit 39f08eb.

This was causing buildbot failures because we were using an explicit
python call instead of the python substitution. This leads to failures
on platforms that do not have a binary called python.

Author: boomanaiden154

compiler-rt/test/tsan/ignore_lib0.cpp

@@ -4,11 +4,13 @@
 // RUN: %clangxx_tsan -O1 -fno-builtin %s -DLIB -fPIC -fno-sanitize=thread -shared -o %t-dir/libignore_lib0.so
 // RUN: %clangxx_tsan -O1 %s -L%t-dir -lignore_lib0 %link_libcxx_tsan -o %t
 // RUN: echo running w/o suppressions:
-// RUN: env LD_LIBRARY_PATH=%t-dir${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} %deflake %run %t | FileCheck %s --check-prefix=CHECK-NOSUPP
+// RUN: echo -n %t-dir > %t.ld_library_path
+// RUN: %python -c "if 'LD_LIBRARY_PATH' in __import__('os').environ: print(':' + __import__('os').environ['LD_LIBRARY_PATH'], end='')" >> %t.ld_library_path
+// RUN: env LD_LIBRARY_PATH=%{readfile:%t.ld_library_path} %deflake %run %t | FileCheck %s --check-prefix=CHECK-NOSUPP
 // RUN: echo running with suppressions:
-// RUN: env LD_LIBRARY_PATH=%t-dir${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
+// RUN: env LD_LIBRARY_PATH=%{readfile:%t.ld_library_path} %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
 // RUN: echo running with generic suppression of noninstrumented code:
-// RUN: env LD_LIBRARY_PATH=%t-dir${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} %env_tsan_opts=ignore_noninstrumented_modules=1 %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
+// RUN: env LD_LIBRARY_PATH=%{readfile:%t.ld_library_path} %env_tsan_opts=ignore_noninstrumented_modules=1 %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
 
 // Tests that interceptors coming from a library specified in called_from_lib
 // suppression are ignored.