Replace cc, c++ & cpp with symlinks

In case of installation of both clang and GCC, we want to be able to
switch which one is the default by adapting the cc, c++ & cpp symlinks.

The default behaviour implemented here is to prefer clang over gcc if
they are both installed.

Change-Id: Ic14720cd876d2bf934d345a955cb5789378209e6

distrib/sets/lists/minix/mi

@@ -234,10 +234,12 @@
 ./usr/bin/bzip2				minix-sys
 ./usr/bin/bzip2recover			minix-sys
 ./usr/bin/c++				minix-sys	gcccmds
+./usr/bin/c++				minix-sys	llvm
 ./usr/bin/cal				minix-sys
 ./usr/bin/calendar			minix-sys
 ./usr/bin/cawf				minix-sys
 ./usr/bin/cc				minix-sys	gcccmds
+./usr/bin/cc				minix-sys	llvm
 ./usr/bin/cc1				minix-sys	gcccmds
 ./usr/bin/cc1obj			minix-sys	gcccmds
 ./usr/bin/cc1plus			minix-sys	gcccmds
@@ -266,6 +268,7 @@
 ./usr/bin/compress			minix-sys
 ./usr/bin/cpio				minix-sys
 ./usr/bin/cpp				minix-sys	gcccmds
+./usr/bin/cpp				minix-sys	llvm
 ./usr/bin/cprofalyze			minix-sys
 ./usr/bin/crc				minix-sys
 ./usr/bin/cron				minix-sys

external/bsd/llvm/bin/clang/Makefile

@@ -6,6 +6,12 @@ NOMAN=		yes
 .if !defined(HOSTPROG)
 SYMLINKS+=	clang ${BINDIR}/clang++
 SYMLINKS+=	clang ${BINDIR}/clang-cpp
+
+# if defined(__MINIX)
+SYMLINKS+=	clang ${BINDIR}/cc
+SYMLINKS+=	clang ${BINDIR}/c++
+SYMLINKS+=	clang ${BINDIR}/cpp
+# endif # defined(__MINIX)
 .endif
 
 .include <bsd.init.mk>

external/gpl3/gcc/usr.bin/cpp/Makefile

@@ -3,7 +3,13 @@
 # For ../Makefile.inc and bsd.own.mk
 .include <bsd.init.mk>
 
+.if defined(__MINIX)
+# In case of installation of both clang and GCC, we want to be able to
+# switch which one is the default by adapting the cc, c++ & cpp symlinks
+PROG=		gcpp
+.else
 PROG=		cpp
+.endif # defined(__MINIX)
 SRCS=		gcc.c cppspec.c prefix.c version.c
 
 # XXX
@@ -26,7 +32,13 @@ CPPFLAGS.gcc.c+=	-I${GCCARCH} -I${BACKENDOBJ} -I. \
 		-DDEFAULT_TARGET_MACHINE=\"${MACHINE_GNU_PLATFORM}\" \
 		-DCONFIGURE_SPECS="\"\""
 
+.if defined(__MINIX)
+.if ${HAVE_LLVM:Uno} == "no"
+SYMLINKS=	gcpp ${BINDIR}/cpp
+.endif # ${HAVE_LLVM:Uno} == "no"
+.else
 LINKS=		${BINDIR}/cpp ${BINDIR}/gcpp
+.endif # defined(__MINIX)
 
 TEXINFO=	cpp.texi
 INFOFLAGS=	-I${DIST}/gcc/doc -I${DIST}/gcc/doc/include -I.

external/gpl3/gcc/usr.bin/g++/Makefile

@@ -10,7 +10,13 @@ NOMAN=		# defined
 
 CPPFLAGS+=	-I${BACKENDOBJ}
 
+.if defined(__MINIX)
+.if ${HAVE_LLVM:Uno} == "no"
+SYMLINKS+=	g++ ${BINDIR}/c++
+.endif # ${HAVE_LLVM:Uno} == "no"
+.else
 LINKS+=		${BINDIR}/g++ ${BINDIR}/c++
+.endif # defined(__MINIX)
 
 .include "../Makefile.frontend"
 

external/gpl3/gcc/usr.bin/gcc/Makefile

@@ -7,7 +7,13 @@ SRCS=		gccspec.c
 
 CPPFLAGS+=	-I${BACKENDOBJ}
 
+.if defined(__MINIX)
+.if ${HAVE_LLVM:Uno} == "no"
+SYMLINKS+=	gcc ${BINDIR}/cc
+.endif # ${HAVE_LLVM:Uno} == "no"
+.else
 LINKS+=		${BINDIR}/gcc ${BINDIR}/cc 
+.endif # defined(__MINIX)
 
 MAN=		gcc.1
 MLINKS=		gcc.1 cc.1 gcc.1 g++.1 gcc.1 c++.1