Add abort () to jerry-libc

Added declaration and implementations of `void abort (void)` to
jerry-libc. As the linux implementation relies on the `getpid`
syscall - which has no arguments - `syscall_0` implementations
have been added as well.

`libc_fatal` has been adapted to use the new `abort` function
instead of `exit`. This also made the definition of
`LIBC_FATAL_ERROR_EXIT_CODE` unnecessary.

Finally, the syscall fatal error message was fixed.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

jerry-libc/target/linux/jerry-libc-target.c

@@ -48,17 +48,34 @@ LIBC_UNREACHABLE_STUB_FOR (int raise (int sig_no __attr_unused___))
 #define LIBC_EXIT_ON_ERROR(syscall_ret_val) \
   if ((syscall_ret_val) < 0) \
 { \
-  libc_fatal ("Syscall successful", __FILE__, __FUNCTION__, __LINE__); \
+  libc_fatal ("Syscall", __FILE__, __FUNCTION__, __LINE__); \
 }
 
+static long int syscall_0 (long int syscall_no);
 static long int syscall_1 (long int syscall_no, long int arg1);
 static long int syscall_2 (long int syscall_no, long int arg1, long int arg2);
 static long int syscall_3 (long int syscall_no, long int arg1, long int arg2, long int arg3);
 
+extern long int syscall_0_asm (long int syscall_no);
 extern long int syscall_1_asm (long int syscall_no, long int arg1);
 extern long int syscall_2_asm (long int syscall_no, long int arg1, long int arg2);
 extern long int syscall_3_asm (long int syscall_no, long int arg1, long int arg2, long int arg3);
 
+/**
+ * System call with no argument.
+ *
+ * @return syscall's return value
+ */
+static __attr_noinline___ long int
+syscall_0 (long int syscall_no) /**< syscall number */
+{
+  long int ret = syscall_0_asm (syscall_no);
+
+  LIBC_EXIT_ON_ERROR (ret);
+
+  return ret;
+} /* syscall_0 */
+
 /**
  * System call with one argument.
  *
@@ -153,6 +170,25 @@ exit (int status) /**< status code */
   }
 } /* exit */
 
+/**
+ * Abort current process, producing an abnormal program termination.
+ * The function raises the SIGABRT signal.
+ */
+void __attr_noreturn___ __attr_used___
+abort (void)
+{
+  syscall_1 (__NR_close, (long int)stdin);
+  syscall_1 (__NR_close, (long int)stdout);
+  syscall_1 (__NR_close, (long int)stderr);
+
+  syscall_2 (__NR_kill, syscall_0 (__NR_getpid), SIGABRT);
+
+  while (true)
+  {
+    /* unreachable */
+  }
+} /* abort */
+
 /**
  * fopen
  *