build: Add support for TCC in RISC-V.

For RISC-V TCC needs a modified libc because it doesn't support Extended
Assembly. This change enables that kind of behavior, letting us select
the TCC library when it is present.

* build-aux/bootstrap.sh.in: Add a block to build-source-lib for TCC.
* build-aux/configure-lib.sh: Guard TCC to remove repeated definitions
from its libc.
* build-aux/install.sh.in: Make it install TCC's library, too

build-aux/bootstrap.sh.in

@@ -142,3 +142,14 @@ cp bin/mes-mescc bin/mes
     fi
     @SHELL@ ${srcdest}build-aux/build-source-lib.sh
 )
+(
+    mkdir -p tcc-lib
+    cp config.sh tcc-lib
+    cd tcc-lib
+    compiler=tcc
+    if test -z "$srcdest"; then
+        srcdest=../
+        srcdir=../
+    fi
+    ${SHELL} ${srcdest}build-aux/build-source-lib.sh
+)

build-aux/configure-lib.sh

@@ -108,8 +108,16 @@ lib/mes/ntoab.c
 lib/mes/oputc.c
 lib/mes/ultoa.c
 lib/mes/utoa.c
+"
+
+# /include/mes/lib-cc.h already defines __raise.c as a macro for __TCC__
+# if we include it in the target source lib it explodes when reading the
+# function definition
+if test $compiler != tcc; then
+    libmes_SOURCES="$libmes_SOURCES
 lib/stub/__raise.c
 "
+fi
 
 if test $mes_libc = mes; then
     libmes_SOURCES="$libmes_SOURCES

build-aux/install.sh.in

@@ -114,6 +114,9 @@ fi
 if test -d mescc-lib/$mes_cpu-mes; then
     tar -cf- -C mescc-lib $mes_cpu-mes | tar -${v}xf- -C $DESTDIR$libdir
 fi
+if test -d tcc-lib/$mes_cpu-mes; then
+    tar -cf- -C tcc-lib/$mes_cpu-mes . | tar -${v}xf- -C $DESTDIR$libdir
+fi
 
 mkdir -p ${DESTDIR}${guile_site_dir}
 mkdir -p ${DESTDIR}${guile_site_ccache_dir}