Timestamp: support %A and %B

These are defined both by [1] and [2] to give full names of a weekday
and month.

[1] http://pubs.opengroup.org/onlinepubs/009695399/functions/strftime.html
[2] https://msdn.microsoft.com/de-de/library/fe06s4ak.aspx

Help/command/string.rst

@@ -324,6 +324,7 @@ specifiers:
    %j        The day of the current year (001-366).
    %m        The month of the current year (01-12).
    %b        Abbreviated month name (e.g. Oct).
+   %B        Full month name (e.g. October).
    %M        The minute of the current hour (00-59).
    %s        Seconds since midnight (UTC) 1-Jan-1970 (UNIX time).
    %S        The second of the current minute.
@@ -331,6 +332,7 @@ specifiers:
    %U        The week number of the current year (00-53).
    %w        The day of the current week. 0 is Sunday. (0-6)
    %a        Abbreviated weekday name (e.g. Fri).
+   %A        Full weekday name (e.g. Friday).
    %y        The last two digits of the current year (00-99)
    %Y        The current year.
 

Help/release/dev/timestamp.rst

@@ -0,0 +1,5 @@
+timestamp
+---------
+
+* The :command:`string(TIMESTAMP)` command now supports ``%A``
+  for full weekday name and ``%B`` for full month name.

Source/cmTimestamp.cxx

@@ -123,7 +123,9 @@ std::string cmTimestamp::AddTimestampComponent(char flag,
 
   switch (flag) {
     case 'a':
+    case 'A':
     case 'b':
+    case 'B':
     case 'd':
     case 'H':
     case 'I':

Tests/RunCMake/string/Timestamp-stderr.txt

@@ -1 +1 @@
-RESULT=2005-08-07 23:19:49 Sun Aug 05 day=219 wd=0 week=32 %I=11 epoch=1123456789
+RESULT=2005-08-07 23:19:49 Sunday=Sun August=Aug 05 day=219 wd=0 week=32 %I=11 epoch=1123456789

Tests/RunCMake/string/Timestamp.cmake

@@ -1,3 +1,3 @@
 set(ENV{SOURCE_DATE_EPOCH} "1123456789")
-string(TIMESTAMP RESULT "%Y-%m-%d %H:%M:%S %a %b %y day=%j wd=%w week=%U %%I=%I epoch=%s" UTC)
+string(TIMESTAMP RESULT "%Y-%m-%d %H:%M:%S %A=%a %B=%b %y day=%j wd=%w week=%U %%I=%I epoch=%s" UTC)
 message("RESULT=${RESULT}")