Add script to create amalgamated build

Fixes: #688

Author: bnoordhuis

amalgam.js

@@ -0,0 +1,46 @@
+import {loadFile, writeFile} from "qjs:std"
+
+const cutils_c = loadFile("cutils.c")
+const cutils_h = loadFile("cutils.h")
+const libbf_c = loadFile("libbf.c")
+const libbf_h = loadFile("libbf.h")
+const libregexp_c = loadFile("libregexp.c")
+const libregexp_h = loadFile("libregexp.h")
+const libregexp_opcode_h = loadFile("libregexp-opcode.h")
+const libunicode_c = loadFile("libunicode.c")
+const libunicode_h = loadFile("libunicode.h")
+const libunicode_table_h = loadFile("libunicode-table.h")
+const list_h = loadFile("list.h")
+const quickjs_atom_h = loadFile("quickjs-atom.h")
+const quickjs_c = loadFile("quickjs.c")
+const quickjs_c_atomics_h = loadFile("quickjs-c-atomics.h")
+const quickjs_h = loadFile("quickjs.h")
+const quickjs_libc_c = loadFile("quickjs-libc.c")
+const quickjs_libc_h = loadFile("quickjs-libc.h")
+const quickjs_opcode_h = loadFile("quickjs-opcode.h")
+
+let source = "#if defined(CONFIG_QUICKJS_LIBC) && defined(__linux__) && !defined(_GNU_SOURCE)\n"
+           + "#define _GNU_SOURCE\n"
+           + "#endif\n"
+           + quickjs_c_atomics_h
+           + cutils_h
+           + list_h
+           + libbf_h
+           + libunicode_h // exports lre_is_id_start, used by libregexp.h
+           + libregexp_h
+           + libunicode_table_h
+           + quickjs_h
+           + quickjs_c
+           + cutils_c
+           + libbf_c
+           + libregexp_c
+           + libunicode_c
+           + "#ifdef CONFIG_QUICKJS_LIBC\n"
+           + quickjs_libc_h
+           + quickjs_libc_c
+           + "#endif // CONFIG_QUICKJS_LIBC\n"
+source = source.replace(/#include "quickjs-atom.h"/g, quickjs_atom_h)
+source = source.replace(/#include "quickjs-opcode.h"/g, quickjs_opcode_h)
+source = source.replace(/#include "libregexp-opcode.h"/g, libregexp_opcode_h)
+source = source.replace(/#include "[^"]+"/g, "")
+writeFile("quickjs-amalgam.c", source)

quickjs-libc.c

@@ -94,7 +94,9 @@ extern char **environ;
 #include "list.h"
 #include "quickjs-libc.h"
 
+#ifndef MAX_SAFE_INTEGER // already defined in amalgamation builds
 #define MAX_SAFE_INTEGER (((int64_t) 1 << 53) - 1)
+#endif
 
 #ifndef QJS_NATIVE_MODULE_SUFFIX
 #ifdef _WIN32