Merge branch 'topic/lsp_os' into 'master'

Avoid `OS` environment, because `libgpr2` introduced

Closes #1628

See merge request eng/ide/ada_language_server!1979

Author: reznikmm

Makefile

@@ -14,12 +14,13 @@ PROCESSORS ?= 0
 ifeq ($(OS),Windows_NT)
    PYTHON=python.exe
    EXE=.exe
+   LSP_OS=$(OS)
 else
    UNAME_S := $(shell uname -s)
    ifeq ($(UNAME_S),Linux)
-      OS=unix
+      LSP_OS=unix
    else ifeq ($(UNAME_S),Darwin)
-      OS=osx
+      LSP_OS=osx
    endif
    PYTHON=python3
    EXE=
@@ -77,7 +78,7 @@ endif
 VSCE=npx vsce
 
 LIBRARY_FLAGS=-XBUILD_MODE=$(BUILD_MODE)	\
-              -XOS=$(OS)			\
+              -XLSP_OS=$(LSP_OS)		\
               -XLIBRARY_TYPE=$(LIBRARY_TYPE)	\
               -XXMLADA_BUILD=$(LIBRARY_TYPE)	\
 	      -XGPR_BUILD=$(LIBRARY_TYPE)

gnat/lsp_server.gpr

@@ -26,8 +26,7 @@ project LSP_Server is
    Library_Type : Library_Kind := external("ALS_LIBRARY_TYPE",
                                   external("LIBRARY_TYPE", "relocatable"));
 
-   type OS_KIND is ("Windows_NT", "unix", "osx");
-   OS : OS_KIND := external("OS", "unix");
+   OS : LSP_Common.OS_API_KIND := LSP_Common.OS_API;
 
    for Source_Dirs use
      ("../source/server",

subprojects/als.toml

@@ -13,11 +13,11 @@ tags = ["lsp", "vscode"]
 ADA_PROJECT_PATH.set= "${CRATE_ROOT}/subprojects/stubs"
 
 [gpr-set-externals."case(os)".linux]
-OS = "unix"
+LSP_OS = "unix"
 [gpr-set-externals."case(os)".macos]
-OS = "osx"
+LSP_OS = "osx"
 [gpr-set-externals."case(os)".windows]
-OS = "Windows_NT"
+LSP_OS = "Windows_NT"
 
 [[depends-on]]
 gnatcoll         = "^24.0.0"

subprojects/spawn.toml

@@ -14,9 +14,9 @@ tags = ["process", "launch", "pipe"]
 disabled = true
 
 [gpr-externals]
-OS = ["unix", "osx", "Windows_NT"]
+SPAWN_OS = ["unix", "osx", "Windows_NT"]
 
 [gpr-set-externals.'case(os)']
-linux   = { OS = "unix" } # Compact table syntax is convenient in this case
-windows = { OS = "Windows_NT" }  # to see all enumeration values, one per row.
-macos   = { OS = "osx" }
+linux   = { SPAWN_OS = "unix" } # Compact table syntax is convenient in this case
+windows = { SPAWN_OS = "Windows_NT" }  # to see all enumeration values, one per row.
+macos   = { SPAWN_OS = "osx" }