configure: Work around a Bash 3 bug

Before Bash 4, the `command` builtin did not work properly in AND-OR
lists when set -e was active, leading to

    set -e
    command nonesuch || echo none

failing without echoing.  Work around it by runing `command nproc` in a
subshell.

Link: https://stackoverflow.com/q/68143965

1 files changed, 3 insertions, 1 deletions

diff --git a/configure b/configure
index 1842078..ab62aa6 100755
--- a/configure
+++ b/configure
@@ -87,7 +87,9 @@ invalid() {
 # Get the number of cores to use
 nproc() {
     {
-        command nproc \
+        # Run command nproc in a subshell to work around a bash 3 bug
+        # https://stackoverflow.com/q/68143965
+        (command nproc) \
             || sysctl -n hw.ncpu \
             || getconf _NPROCESSORS_ONLN \
             || echo 1