Changed every 'fpic' variant to 'pic' (#4969)

* Changed every 'fpic' variant to 'pic'. fixes #2463

Every variant that activates compilation of position independent code
has been changed to 'pic'. Hardcoded compiler flags in packages have
been substituted with `self.compiler.pic_flag`.

* Changed literal uses of '-fpic' to 'self.compiler.pic_flag'

var/spack/repos/builtin/packages/scotch/package.py

@@ -129,7 +129,9 @@ def configure(self):
             if self.spec.satisfies('platform=darwin'):
                 makefile_inc.extend([
                     'LIB       = .dylib',
-                    'CLIBFLAGS = -dynamiclib -fPIC',
+                    'CLIBFLAGS = -dynamiclib {0}'.format(
+                        self.compiler.pic_flag
+                    ),
                     'RANLIB    = echo',
                     'AR        = $(CC)',
                     'ARFLAGS   = -dynamiclib $(LDFLAGS) -Wl,-install_name -Wl,%s/$(notdir $@) -undefined dynamic_lookup -o ' % prefix.lib  # noqa
@@ -137,12 +139,12 @@ def configure(self):
             else:
                 makefile_inc.extend([
                     'LIB       = .so',
-                    'CLIBFLAGS = -shared -fPIC',
+                    'CLIBFLAGS = -shared {0}'.format(self.compiler.pic_flag),
                     'RANLIB    = echo',
                     'AR        = $(CC)',
                     'ARFLAGS   = -shared $(LDFLAGS) -o'
                 ])
-            cflags.append('-fPIC')
+            cflags.append(self.compiler.pic_flag)
         else:
             makefile_inc.extend([
                 'LIB       = .a',