[Ada] Fix indentation of "Start of processing for ..." labels

The "Start of processing for ..." labels should be aligned with the
BEGIN that follows. Violations found with:

$ grep -Pzo "( *)   \-\-  Start of processing for \w+\n\n\1begin" *.adb

and corrected manually, because some of them had to be entirely removed.

Also, remove trailing semicolons found while guessing the grep pattern.

gcc/ada/

	* exp_aggr.adb, exp_ch3.adb, exp_util.adb, freeze.adb,
	gnatfind.adb, gnatlink.adb, gnatxref.adb, gprep.adb,
	libgnat/a-cfhama.adb, libgnat/g-alleve.adb, sem_ch12.adb,
	sem_ch13.adb, xr_tabls.adb: Fix style labels.

gcc/ada/exp_aggr.adb

@@ -7542,7 +7542,7 @@ package body Exp_Aggr is
 
       end Expand_Iterated_Component;
 
-      --  Start of processing for Expand_Container_Aggregate
+   --  Start of processing for Expand_Container_Aggregate
 
    begin
       Parse_Aspect_Aggregate (Asp,

gcc/ada/exp_ch3.adb

@@ -1288,8 +1288,6 @@ package body Exp_Ch3 is
       Comp      : Entity_Id;
       Comp_Type : Entity_Id;
 
-      --  Start of processing for Build_Equivalent_Record_Aggregate
-
    begin
       if not Is_Record_Type (T)
         or else Has_Discriminants (T)

gcc/ada/exp_util.adb

@@ -6468,7 +6468,7 @@ package body Exp_Util is
          return Empty;
       end Check_Decls;
 
-      --  Start of processing for Following_Address_Clause
+   --  Start of processing for Following_Address_Clause
 
    begin
       --  If parser detected no address clause for the identifier in question,

gcc/ada/freeze.adb

@@ -3581,7 +3581,7 @@ package body Freeze is
                      end if;
                   end Complain_CS;
 
-                  --  Start of processing for Alias_Atomic_Check
+               --  Start of processing for Alias_Atomic_Check
 
                begin
                   --  If object size of component type isn't known, we cannot

gcc/ada/gnatfind.adb

@@ -86,7 +86,7 @@ procedure Gnatfind is
 
       procedure Check_Version_And_Help is new Check_Version_And_Help_G (Usage);
 
-      --  Start of processing for Parse_Cmd_Line
+   --  Start of processing for Parse_Cmd_Line
 
    begin
       --  First check for --version or --help

gcc/ada/gnatlink.adb

@@ -407,7 +407,7 @@ procedure Gnatlink is
 
       procedure Check_Version_And_Help is new Check_Version_And_Help_G (Usage);
 
-      --  Start of processing for Process_Args
+   --  Start of processing for Process_Args
 
    begin
       --  First, check for --version and --help

gcc/ada/gnatxref.adb

@@ -74,7 +74,7 @@ procedure Gnatxref is
 
       procedure Check_Version_And_Help is new Check_Version_And_Help_G (Usage);
 
-      --  Start of processing for Parse_Cmd_Line
+   --  Start of processing for Parse_Cmd_Line
 
    begin
       --  First check for --version or --help

gcc/ada/gprep.adb

@@ -729,7 +729,7 @@ package body GPrep is
 
       procedure Check_Version_And_Help is new Check_Version_And_Help_G (Usage);
 
-      --  Start of processing for Scan_Command_Line
+   --  Start of processing for Scan_Command_Line
 
    begin
       --  First check for --version or --help

gcc/ada/libgnat/a-cfhama.adb

@@ -151,7 +151,7 @@ is
          Insert (Target, N.Key, N.Element);
       end Insert_Element;
 
-      --  Start of processing for Assign
+   --  Start of processing for Assign
 
    begin
       if Target'Address = Source'Address then

gcc/ada/libgnat/g-alleve.adb

@@ -3779,7 +3779,7 @@ package body GNAT.Altivec.Low_Level_Vectors is
          return D;
       end Saturate;
 
-      --  Start of processing for vpksxus
+   --  Start of processing for vpksxus
 
    begin
       for J in 0 .. N - 1 loop

gcc/ada/sem_ch12.adb

@@ -17192,7 +17192,7 @@ package body Sem_Ch12 is
          end if;
       end Validate_Derived_Type_Default;
 
-      --  Start of processing for Validate_Formal_Type_Default
+   --  Start of processing for Validate_Formal_Type_Default
 
    begin
       Analyze (Default);

gcc/ada/sem_ch13.adb

@@ -12449,7 +12449,7 @@ package body Sem_Ch13 is
                OC_Lbit (To) := OC_Lbit (From);
             end OC_Move;
 
-            --  Start of processing for Overlap_Check
+         --  Start of processing for Overlap_Check
 
          begin
             CC := First (Component_Clauses (N));

gcc/ada/xr_tabls.adb

@@ -819,7 +819,7 @@ package body Xr_Tabls is
          end if;
       end Internal_Strip;
 
-   --  Start of processing for Get_File;
+   --  Start of processing for Get_File
 
    begin
       --  If we do not want the full path name