[gnome-software] build: Fix meson check for libm

[Christophe Fergeau <teuf src gnome org>]

commit 8dde78a87f6e448dc9fc91ece382a49f2a275c5a
Author: Christophe Fergeau <cfergeau redhat com>
Date:   Sun Aug 27 14:34:24 2017 +0200

    build: Fix meson check for libm
    
    The test should be cc.find_library('m', required: false) rather than
    testing 'libm'. Using libm makes meson look for liblibm, which is not
    going to exist.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786859
    
    Signed-off-by: Christophe Fergeau <cfergeau redhat com>

 meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/meson.build b/meson.build
index 099ffc1..544f40e 100644
--- a/meson.build
+++ b/meson.build
@@ -98,7 +98,7 @@ gio_unix = dependency('gio-unix-2.0')
 gmodule = dependency('gmodule-2.0')
 gtk = dependency('gtk+-3.0', version : '>= 3.20.0')
 json_glib = dependency('json-glib-1.0', version : '>= 1.1.1')
-libm = cc.find_library('libm', required: false)
+libm = cc.find_library('m', required: false)
 libsecret = dependency('libsecret-1')
 libsoup = dependency('libsoup-2.4', version : '>= 2.51.92')
 sqlite3 = dependency('sqlite3')