csource building prefers bin/nim (#21115)

tools/niminst/niminst.nim

@@ -515,6 +515,17 @@ template gatherFiles(fun, libpath, outDir) =
     # commenting out for now, see discussion in https://github.com/nim-lang/Nim/pull/13413
     # copySrc(libpath / "lib/wrappers/linenoise/linenoise.h")
 
+proc exe(f: string): string =
+  result = addFileExt(f, ExeExt)
+  when defined(windows):
+    result = result.replace('/','\\')
+
+proc findNim(): string =
+  let nim = "nim".exe
+  result = quoteShell("bin" / nim)
+  if not fileExists(result):
+    result = "nim"
+
 proc srcdist(c: var ConfigData) =
   let cCodeDir = getOutputDir(c) / "c_code"
   if not dirExists(cCodeDir): createDir(cCodeDir)
@@ -533,10 +544,10 @@ proc srcdist(c: var ConfigData) =
       var dir = getOutputDir(c) / buildDir(osA, cpuA)
       if dirExists(dir): removeDir(dir)
       createDir(dir)
-      var cmd = ("nim compile -f --symbolfiles:off --compileonly " &
+      var cmd = ("$# compile -f --symbolfiles:off --compileonly " &
                  "--gen_mapping --cc:gcc --skipUserCfg" &
                  " --os:$# --cpu:$# $# $#") %
-                 [osname, cpuname, c.nimArgs, c.mainfile]
+                 [findNim(), osname, cpuname, c.nimArgs, c.mainfile]
       echo(cmd)
       if execShellCmd(cmd) != 0:
         quit("Error: call to nim compiler failed")