Rename crt1.o to crt0.o and install compatibility crt1.o.

This prepares for an incompatible compiler toolchain change scheduled for
Sortix 0.10 development where crt0.o is used instead of crt1.o.

libc/Makefile

@@ -622,6 +622,7 @@ $(FREEOBJS) \
 $(HOSTEDOBJS) \
 
 CRTOBJ=\
+crt0.o \
 crt1.o \
 crti.o \
 crtn.o \
@@ -671,9 +672,12 @@ libk.a: $(LIBK_OBJS)
 librt.a:
 	$(HOSTAR) rcs $@
 
-crt1.o: $(CPUDIR)/crt1.o
+crt0.o: $(CPUDIR)/crt0.o
 	ln -f $< $@
 
+crt1.o: crt0.o
+	cp $< $@
+
 crti.o: $(CPUDIR)/crti.o
 	ln -f $< $@
 

libc/x64/crt0.S

@@ -17,7 +17,7 @@
     You should have received a copy of the GNU Lesser General Public License
     along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
 
-    x64/crt1.S
+    x64/crt0.S
     Implement the _start symbol at which execution begins which performs the
     task of initializing the standard library and executing the main function.
 

libc/x86/crt0.S

@@ -17,7 +17,7 @@
     You should have received a copy of the GNU Lesser General Public License
     along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
 
-    x86/crt1.S
+    x86/crt0.S
     Implement the _start symbol at which execution begins which performs the
     task of initializing the standard library and executing the main function.