Eliminate name clash with system signal.h header file.

Tried to solve the signal.h name clash by using #include_next, but
seeing as this is not recommended[1] and breaks builds on some cross
compilers, the files were simply renamed: signal.[ch] --> sig.[ch]

[1] - http://gcc.gnu.org/onlinedocs/cpp/Wrapper-Headers.html

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

sig.h

@@ -0,0 +1,70 @@
+/* Signal management - Be conservative with what finit responds to!
+ *
+ * Copyright (c) 2008-2010  Claudio Matsuoka <cmatsuoka@gmail.com>
+ * Copyright (c) 2008-2012  Joachim Nilsson <troglobit@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef FINIT_SIG_H_
+#define FINIT_SIG_H_
+
+#include <signal.h>
+
+#define SYNC_SHUTDOWN   "/var/lock/finit.shutdown"
+#define SYNC_STOPPED    "/var/lock/finit.stopped"
+
+#define SETSIG(sa, sig, fun, flags)			\
+	do {						\
+		sa.sa_sigaction = fun;			\
+		sa.sa_flags = SA_SIGINFO | flags;	\
+		sigemptyset(&sa.sa_mask);		\
+		sigaction(sig, &sa, NULL);		\
+	} while (0)
+
+#define IGNSIG(sa, sig, flags)			\
+	do {					\
+		sa.sa_handler = SIG_IGN;	\
+		sa.sa_flags = flags;		\
+		sigemptyset(&sa.sa_mask);	\
+		sigaction(sig, &sa, NULL);	\
+	} while (0)
+
+#define DFLSIG(sa, sig, flags)                  \
+        do {                                    \
+                sa.sa_handler = SIG_DFL;        \
+                sa.sa_flags = flags;            \
+                sigemptyset(&sa.sa_mask);       \
+                sigaction(sig, &sa, NULL);      \
+        } while (0)
+
+void do_shutdown    (int sig);
+int  sig_stopped    (void);
+void sig_init       (void);
+void sig_setup      (void);
+
+#endif /* FINIT_SIG_H_ */
+
+/**
+ * Local Variables:
+ *  version-control: t
+ *  indent-tabs-mode: t
+ *  c-file-style: "linux"
+ * End:
+ */