Fix typographical and grammatical errors and inconsistencies.

The initial list of hits was generated with the codespell command
below, and each hit was evaluated and fixed manually while taking
context into consideration.

    DIRS="kernel/ frontends/ backends/ passes/ techlibs/"
    DIRS="${DIRS} libs/ezsat/ libs/subcircuit"
    codespell $DIRS -S *.o -L upto,iff,thru,synopsys,uint

More hits were found by looking through comments and strings manually.

1 files changed, 1 insertions, 1 deletions

diff --git a/passes/opt/opt_expr.cc b/passes/opt/opt_expr.cc
index 610edc5e9..998c6507c 100644
--- a/passes/opt/opt_expr.cc
+++ b/passes/opt/opt_expr.cc
@@ -1477,7 +1477,7 @@ struct OptExprPass : public Pass {
 		log("    opt_expr [options] [selection]\n");
 		log("\n");
 		log("This pass performs const folding on internal cell types with constant inputs.\n");
-		log("It also performs some simple expression rewritring.\n");
+		log("It also performs some simple expression rewriting.\n");
 		log("\n");
 		log("    -mux_undef\n");
 		log("        remove 'undef' inputs from $mux, $pmux and $_MUX_ cells\n");