gc, cc: avoid using the wrong library when building the compilers

This can happen on Plan 9 if we we're building
with the 32-bit and 64-bit host compilers, one
after the other.

R=rsc
CC=golang-dev
https://golang.org/cl/5599053

.hgignore

@@ -3,7 +3,7 @@ syntax:glob
 .git
 .gitignore
 *.[568ao]
-*.ao
+*.a[568o]
 *.so
 *.pyc
 ._*

src/cmd/5c/Makefile

@@ -26,7 +26,7 @@ OFILES=\
 	../5l/enam.$O\
 
 LIB=\
-	../cc/cc.a\
+	../cc/cc.a$O\
 
 include ../../Make.ctool
 

src/cmd/5g/Makefile

@@ -28,7 +28,7 @@ OFILES=\
 	reg.$O\
 
 LIB=\
-	../gc/gc.a\
+	../gc/gc.a$O\
 
 include ../../Make.ctool
 

src/cmd/6c/Makefile

@@ -28,7 +28,7 @@ OFILES=\
 	../6l/enam.$O\
 
 LIB=\
-	../cc/cc.a\
+	../cc/cc.a$O\
 
 include ../../Make.ctool
 

src/cmd/6g/Makefile

@@ -27,7 +27,7 @@ OFILES=\
 	reg.$O\
 
 LIB=\
-	../gc/gc.a\
+	../gc/gc.a$O\
 
 include ../../Make.ctool
 

src/cmd/8c/Makefile

@@ -29,7 +29,7 @@ OFILES=\
 	../8l/enam.$O\
 
 LIB=\
-	../cc/cc.a\
+	../cc/cc.a$O\
 
 include ../../Make.ctool
 

src/cmd/8g/Makefile

@@ -28,7 +28,7 @@ OFILES=\
 	reg.$O\
 
 LIB=\
-	../gc/gc.a\
+	../gc/gc.a$O\
 
 include ../../Make.ctool
 

src/cmd/cc/Makefile

@@ -5,7 +5,7 @@
 include ../../Make.inc
 O:=$(HOST_O)
 
-LIB=cc.a
+LIB=cc.a$O
 
 HFILES=\
 	cc.h\

src/cmd/gc/Makefile

@@ -5,7 +5,7 @@
 include ../../Make.inc
 O:=$(HOST_O)
 
-LIB=gc.a
+LIB=gc.a$O
 
 HFILES=\
 	go.h\

src/cmd/gc/go.h

@@ -4,6 +4,8 @@
 
 #include	<bio.h>
 
+#pragma	lib	"../gc/gc.a$O"
+
 #undef OAPPEND
 
 // avoid <ctype.h>