sage.env.cython_aliases: Do not fail if one of the listed libraries i…

…s not known to pkgconfig

src/sage/env.py

@@ -420,9 +420,15 @@ def cython_aliases():
                 pc = defaultdict(list, {'libraries': ['z']})
                 libs = "-lz"
         else:
-            aliases[var + "CFLAGS"] = pkgconfig.cflags(lib).split()
-            pc = pkgconfig.parse(lib)
-            libs = pkgconfig.libs(lib)
+            try:
+                aliases[var + "CFLAGS"] = pkgconfig.cflags(lib).split()
+                pc = pkgconfig.parse(lib)
+                libs = pkgconfig.libs(lib)
+            except pkgconfig.PackageNotFoundError:
+                from distutils import log
+                log.warn('Package {0} not installed'.format(lib))
+                continue
+
         # It may seem that INCDIR is redundant because the -I options are also
         # passed in CFLAGS.  However, "extra_compile_args" are put at the end
         # of the compiler command line.  "include_dirs" go to the front; the
@@ -454,7 +460,9 @@ def uname_specific(name, value, alternative):
     # file (possibly because of confusion between CFLAGS and CXXFLAGS?).
     # This is not a problem in practice since LinBox depends on
     # fflas-ffpack and fflas-ffpack does add such a C++11 flag.
-    aliases["LINBOX_CFLAGS"].append("-std=gnu++11")
+    if "LINBOX_CFLAGS" in aliases:
+        aliases["LINBOX_CFLAGS"].append("-std=gnu++11")
+
     aliases["ARB_LIBRARY"] = ARB_LIBRARY
 
     # TODO: Remove Cygwin hack by installing a suitable cblas.pc
@@ -463,7 +471,7 @@ def uname_specific(name, value, alternative):
 
     try:
         aliases["M4RI_CFLAGS"].remove("-pedantic")
-    except ValueError:
+    except (ValueError, KeyError):
         pass
 
     # Determine ecl-specific compiler arguments using the ecl-config script