[Ada] Fix PR ada/104767

[Eric Botcazou via Gcc-patches]

This is a regression present on mainline, 11 and 10 branches.  When the serial 
port is closed, we need to ensure that the port handle is properly reset for 
it to be detected as closed.

Tested on x86-64/Linux, applied on mainline, 11 and 10 branches.


2022-03-24  Pascal Obry  <o...@adacore.com>

        PR ada/104767
        * libgnat/g-sercom__mingw.adb (Close): Reset port handle to -1.
        * libgnat/g-sercom__linux.adb (Close): Likewise.

-- 
Eric Botcazou
diff --git a/gcc/ada/libgnat/g-sercom__linux.adb b/gcc/ada/libgnat/g-sercom__linux.adb
index a2a64b1c17f..73bbb69300e 100644
--- a/gcc/ada/libgnat/g-sercom__linux.adb
+++ b/gcc/ada/libgnat/g-sercom__linux.adb
@@ -382,6 +382,7 @@ package body GNAT.Serial_Communications is
    begin
       if Port.H /= -1 then
          Res := close (int (Port.H));
+         Port.H := -1;
       end if;
    end Close;
 
diff --git a/gcc/ada/libgnat/g-sercom__mingw.adb b/gcc/ada/libgnat/g-sercom__mingw.adb
index aea78aead8c..d3301bd045b 100644
--- a/gcc/ada/libgnat/g-sercom__mingw.adb
+++ b/gcc/ada/libgnat/g-sercom__mingw.adb
@@ -70,6 +70,7 @@ package body GNAT.Serial_Communications is
    begin
       if Port.H /= -1 then
          Success := CloseHandle (HANDLE (Port.H));
+         Port.H := -1;
 
          if Success = Win32.FALSE then
             Raise_Error ("error closing the port");