Fix a few places we modify the techlef and don't mark it modified

sky130/custom/scripts/fix_techlefA.py

diff --git a/sky130/custom/scripts/fix_techlefA.py b/sky130/custom/scripts/fix_techlefA.py
index 6c61f54..c19b02e 100755
--- a/sky130/custom/scripts/fix_techlefA.py
+++ b/sky130/custom/scripts/fix_techlefA.py
@@ -57,6 +57,7 @@
                 ematch = emptyrex.match(line)
                 if ematch:
                     fixedlines.append('  MINENCLOSEDAREA 0.14 ;')
+                    modified = True
 
         rmatch = resrex2.match(line)
         if rmatch:

sky130/custom/scripts/fix_techlefB.py

diff --git a/sky130/custom/scripts/fix_techlefB.py b/sky130/custom/scripts/fix_techlefB.py
index f34b51b..3fad5bb 100755
--- a/sky130/custom/scripts/fix_techlefB.py
+++ b/sky130/custom/scripts/fix_techlefB.py
@@ -74,6 +74,7 @@
                 ematch = emptyrex.match(line)
                 if ematch:
                     fixedlines.append('  MINENCLOSEDAREA 0.14 ;')
+                    modified = True
 
         # Check for the MANUFACTURINGGRID statement in the file, and
         # add the USEMINSPACING statement after it.