gnu: zstd: Fix linking to pthread on the Hurd.

* gnu/packages/compression.scm (zstd) <#:make-flags> [hurd]: Add
"PCMTLIB=-pthread".

Change-Id: I0fb3ff872d223197ea86831917924e185ef2591c

1 files changed, 4 insertions, 0 deletions

diff --git a/gnu/packages/compression.scm b/gnu/packages/compression.scm
index ab2f595eb85..a7146cd1505 100644
--- a/gnu/packages/compression.scm
+++ b/gnu/packages/compression.scm
@@ -1850,6 +1850,10 @@ or junctions, and always follows hard links.")
                             ;; This isn't picked up correctly in the Makefiles.
                             "EXT=.exe")
                           '())
+                   #$@(if (target-hurd?)
+                          ;; Uses symbols from pthread.
+                          `("PCMTLIB=-pthread")
+                          '())
                    ;; Auto-detection is over-engineered and buggy.
                    "PCLIBDIR=lib"
                    "PCINCDIR=include"