[LyX/master] Add default path to server pipe (cmake build + unix)

[Kornel Benko]

commit 689f26d2476e710ce7b04445ced9b91039494f04
Author: Kornel Benko <kornel at lyx.org>
Date:   Fri Apr 17 18:38:51 2020 +0200

    Add default path to server pipe (cmake build + unix)
    
    Actually the change is affecting only builds if
    1.) Using cmake build
    2.) on unix
    
    To use it on
      cygwin: one has to patch development/cygwin/lyxrc.dist.in
      MacOSX:     -//-         development/MacOSX/lyxrc.dist.in
    
    We need also a Windows-version
    
    Also the compilation with automake lacks the handling of development/unix/lyxrc.dist.in
---
 development/unix/lyxrc.dist.in |    1 +
 src/LyXRC.cpp                  |    3 ++-
 2 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/development/unix/lyxrc.dist.in b/development/unix/lyxrc.dist.in
index 3b10a81..6e64df1 100644
--- a/development/unix/lyxrc.dist.in
+++ b/development/unix/lyxrc.dist.in
@@ -13,4 +13,5 @@
 Format 25
 
 \texinputs_prefix ".:@LYX_ABS_INSTALLED_DATADIR at tex"
+\serverpipe "$$User/.lyxpipe"
 
diff --git a/src/LyXRC.cpp b/src/LyXRC.cpp
index f7c085c..3b0add1 100644
--- a/src/LyXRC.cpp
+++ b/src/LyXRC.cpp
@@ -670,7 +670,8 @@ LyXRC::ReturnValues LyXRC::read(Lexer & lexrc, bool check_format)
 
 		case RC_SERVERPIPE:
 			if (lexrc.next())
-				lyxpipes = os::internal_path(lexrc.getString());
+				lyxpipes = subst(os::internal_path(lexrc.getString()), "$$User",
+					package().user_support().absFileName());
 			break;
 
 		case RC_CT_ADDITIONS_UNDERLINED: