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/superlu/package.py

@@ -38,7 +38,7 @@ class Superlu(Package):
     version('5.2.1', '3a1a9bff20cb06b7d97c46d337504447')
     version('4.3', 'b72c6309f25e9660133007b82621ba7c')
 
-    variant('fpic',    default=True,
+    variant('pic',    default=True,
             description='Build with position independent code')
 
     depends_on('cmake', when='@5.2.1:', type='build')
@@ -51,7 +51,7 @@ def install(self, spec, prefix):
             '-DBLAS_blas_LIBRARY={0}'.format(spec['blas'].libs.joined())
         ]
 
-        if '+fpic' in spec:
+        if '+pic' in spec:
             cmake_args.extend([
                 '-DCMAKE_POSITION_INDEPENDENT_CODE=ON'
             ])
@@ -89,7 +89,7 @@ def install(self, spec, prefix):
             'CDEFS      = -DAdd_'
         ])
 
-        if '+fpic' in spec:
+        if '+pic' in spec:
             config.extend([
                 # Use these lines instead when pic_flag capability arrives
                 'CFLAGS     = -O3 {0}'.format(self.compiler.pic_flag),