Allow for Runtime-less build of GDC and GNAT

Both D and GNAT have their own runtimes (resp. libphotos and libada).
It is still possible to build the compiler proper without any runtime,
and have an external runtime installed later. This is most commonly
found in embedded systems.

An example for D is: https://github.com/KitsunebiGames/tinyd-rt
An example for Ada: https://github.com/Fabien-Chouteau/bare_runtime

Signed-off-by: Marc Poulhiès <dkm@kataplop.net>

config/cc.in

@@ -67,18 +67,6 @@ config CC_LANG_JIT
       Only select this if you know that your specific version of the
       compiler supports the libgccjit.
 
-if ! BARE_METAL
-
-config CC_LANG_JAVA
-    bool
-    prompt "Java"
-    depends on CC_SUPPORT_JAVA
-    help
-      Enable building a Java compiler.
-
-      Only select this if you know that your specific version of the
-      compiler supports this language.
-
 config CC_LANG_ADA
     bool
     prompt "Ada (EXPERIMENTAL)"
@@ -88,7 +76,8 @@ config CC_LANG_ADA
       Enable building an Ada compiler.
 
       Only select this if you know that your specific version of the
-      compiler supports this language.
+      compiler supports this language. If the target is bare, the runtime
+      won't be included.
 
 config CC_LANG_D
     bool
@@ -98,6 +87,19 @@ config CC_LANG_D
     help
       Enable building a D compiler.
 
+      Only select this if you know that your specific version of the
+      compiler supports this language. If the target is bare, the runtime
+      won't be included.
+
+if ! BARE_METAL
+
+config CC_LANG_JAVA
+    bool
+    prompt "Java"
+    depends on CC_SUPPORT_JAVA
+    help
+      Enable building a Java compiler.
+
       Only select this if you know that your specific version of the
       compiler supports this language.
 

scripts/build/cc/gcc.sh

@@ -43,7 +43,7 @@ cc_gcc_lang_list() {
     [ "${CT_CC_LANG_CXX}" = "y"      ] && lang_list+=",c++"
     [ "${CT_CC_LANG_FORTRAN}" = "y"  ] && lang_list+=",fortran"
     [ "${CT_CC_LANG_ADA}" = "y"      ] && lang_list+=",ada"
-    [ "${CT_CC_LANG_D}" = "y"      ] && lang_list+=",d"
+    [ "${CT_CC_LANG_D}" = "y"        ] && lang_list+=",d"
     [ "${CT_CC_LANG_JAVA}" = "y"     ] && lang_list+=",java"
     [ "${CT_CC_LANG_JIT}" = "y"      ] && lang_list+=",jit"
     [ "${CT_CC_LANG_OBJC}" = "y"     ] && lang_list+=",objc"
@@ -528,6 +528,22 @@ do_gcc_core_backend() {
         "") extra_config+=("--disable-tls");;
     esac
 
+    # In baremetal, we only build the Ada compiler without its runtime.
+    # The runtime will need to be provided externaly by the user.
+    if [    "${mode}" = "baremetal"    \
+         -a "${CT_CC_LANG_ADA}"  = "y"    \
+       ]; then
+        extra_config+=("--disable-libada" )
+    fi
+
+    # In baremetal, we only build the D compiler without its runtime.
+    # The runtime will need to be provided externaly by the user.
+    if [    "${mode}" = "baremetal"    \
+         -a "${CT_CC_LANG_D}"  = "y"    \
+       ]; then
+        extra_config+=("--disable-libphobos" )
+    fi
+
     # Some versions of gcc have a defective --enable-multilib.
     # Since that's the default, only pass --disable-multilib. For multilib,
     # also enable multiarch. Without explicit --enable-multiarch, core
@@ -710,6 +726,14 @@ do_gcc_core_backend() {
     CT_DoLog EXTRA "Building ${log_txt}"
     CT_DoExecLog ALL make ${CT_JOBSFLAGS} ${core_targets_all}
 
+    # In case of baremetal, the gnat* tools are not built automatically.
+    if [    "${mode}" = "baremetal"    \
+         -a "${CT_CC_LANG_ADA}"  = "y"    \
+       ]; then
+        CT_DoLog EXTRA "Building gnattools for baremetal"
+        CT_DoExecLog ALL make -C gcc ${CT_JOBSFLAGS} cross-gnattools
+    fi
+
     # Do not pass ${CT_JOBSFLAGS} here: recent GCC builds have been failing
     # in parallel 'make install' at random locations: libitm, libcilk,
     # always for the files that are installed more than once to the same