Add gprbuild for runtime

runtime/runtime.gpr

@@ -0,0 +1,49 @@
+library project Runtime is
+
+   for Languages use ("Ada");
+
+   for Library_Auto_Init use "False";
+   for Library_Name use "gnat";
+   for Library_Kind use "static";
+   for Library_Dir use "adalib";
+
+   for Object_Dir use ".build";
+
+   for Source_Dirs use ("adainclude");
+
+   for Target use "arm-eabi";
+
+   for Runtime ("Ada") use Runtime'Project_Dir;
+
+   package Compiler is
+      COMMON_FLAGS := ("-ffunction-sections", "-fdata-sections");
+      COMMON_FLAGS := COMMON_FLAGS & ("-g", "-Og");
+      ALL_ADAFLAGS :=
+         ("-gnatwae", "-gnatpgn", "-gnatqQ", "-nostdinc")
+         & COMMON_FLAGS
+         & external_as_list ("EXTRA_ADAFLAGS", " ");
+
+      ALL_ADAFLAGS := ALL_ADAFLAGS & "-gnata";
+
+      ALL_CFLAGS :=
+         external_as_list("INCLUDES", " ")
+         & external_as_list("DEFINES", " ")
+         & ("-DIN_RTS", "-Dinhibit_libc") & COMMON_FLAGS;
+
+      NO_SIBLING_ADAFLAGS := ("-fno-optimize-sibling-calls");
+      NO_REORDER_ADAFLAGS := ("-fno=toplevel-reorder");
+
+      for Switches ("C") use ALL_CFLAGS;
+      for Switches ("Ada") use ALL_ADAFLAGS;
+   end Compiler;
+
+   package Install is
+      for Prefix use "arm-eabi/lib/gnat/";
+      for Sources_Subdir use "adainclude";
+      for Ali_Subdir use "adalib";
+      for Lib_Subdir use "adalib";
+      for Required_Artifacts (".") use ("runtime.xml");
+      for Install_Project use "false";
+   end Install;
+
+end Runtime;