Resolving conflicting definitions of assert macro

With the insertion of `assert(0)` into the body of `reach_error` it was
necessary to include the `assert.h` system header. Some tasks, however, already
defined the `assert` macro themselves (expanding to calls to `reach_error()`).
To avoid compiler/preprocessor warnings about conflicting macro definitions,
prefix the local `assert` definitions by `#undef assert` to disable the prior
definition.

The changes were done using the following command:
```
for f in c/aws-c-common/prelude.h c/*/*.c
do
perl -i -e \
  '$p = 0; $e = 0;
   while(<>) {
     if(/^#define\s+assert\(\w+\)/) {
       print "#undef assert\n";
     }
     print;
   }' \
  $f
done
```

Author: tautschnig

c/aws-c-common/prelude.h

@@ -23,6 +23,7 @@ void __VERIFIER_assert(_Bool cond) {
 
 #define __CPROVER_size_t unsigned long
 
+#undef assert
 #define assert(cond) \
     __VERIFIER_assert(cond)
 

c/pthread-atomic/dekker.c

@@ -11,6 +11,7 @@ void reach_error() { assert(0); }
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int flag1 = 0, flag2 = 0; // boolean flags

c/pthread-atomic/lamport.c

@@ -7,6 +7,7 @@ void reach_error() { assert(0); }
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int x, y;

c/pthread-atomic/peterson.c

@@ -7,6 +7,7 @@ void reach_error() { assert(0); }
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int flag1 = 0, flag2 = 0; // boolean flags

c/pthread-atomic/qrcu-1.c

@@ -16,6 +16,7 @@ extern int __VERIFIER_nondet_int();
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int idx=0; // boolean to control which of the two elements will be used by readers

c/pthread-atomic/qrcu-2.c

@@ -16,6 +16,7 @@ extern int __VERIFIER_nondet_int();
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int idx=0; // boolean to control which of the two elements will be used by readers

c/pthread-atomic/read_write_lock-1.c

@@ -15,6 +15,7 @@ void reach_error() { assert(0); }
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int w=0, r=0, x, y;

c/pthread-atomic/read_write_lock-2.c

@@ -15,6 +15,7 @@ void reach_error() { assert(0); }
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int w=0, r=0, x, y;

c/pthread-atomic/scull.c

@@ -83,6 +83,7 @@ extern int __VERIFIER_nondet_int();
 
 
 
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 inode i;

c/pthread-atomic/szymanski.c

@@ -7,6 +7,7 @@ void reach_error() { assert(0); }
 */
 
 #include <pthread.h>
+#undef assert
 #define assert(e) if (!(e)) ERROR: reach_error()
 
 int flag1 = 0, flag2 = 0; // integer flags