[xen master] tools/libs: Don't recursively expand MAJOR ?= $(shell ...)

[patchbot@xxxxxxx]

commit a4885765eedbddafcc57bce6cbfcd443d0a7eca9
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon Dec 13 18:49:17 2021 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Dec 16 20:27:12 2021 +0000

    tools/libs: Don't recursively expand MAJOR ?= $(shell ...)
    
    ?= is a deferred assignment.  Switch to an alternative form which lets us 
use
    an immediate assignment.
    
    Before, version.sh gets run anywhere between 46 and 88 times, with 50 on a
    `clean`.  After, between 6 and 12 times.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/libs/libs.mk | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/libs/libs.mk b/tools/libs/libs.mk
index dfbbef4080..b21e0bf083 100644
--- a/tools/libs/libs.mk
+++ b/tools/libs/libs.mk
@@ -6,7 +6,10 @@
 #   MINOR:   minor version of lib (0 if empty)
 
 LIBNAME := $(notdir $(CURDIR))
-MAJOR ?= $(shell $(XEN_ROOT)/version.sh $(XEN_ROOT)/xen/Makefile)
+
+ifeq ($(origin MAJOR), undefined)
+MAJOR := $(shell $(XEN_ROOT)/version.sh $(XEN_ROOT)/xen/Makefile)
+endif
 MINOR ?= 0
 
 SHLIB_LDFLAGS += -Wl,--version-script=libxen$(LIBNAME).map
--
generated by git-patchbot for /home/xen/git/xen.git#master