Align structures 8 byte for 64-bit platforms

[GermanAizek]

Migrated from here: https://salsa.debian.org/debian/htop/-/merge_requests/7

This PR will decrease costs copying, moving, and creating object-structures only for common 64bit processors due to the 8-byte data alignment.

Smaller size structure or class, higher chance putting into CPU cache. Most processors are already 64 bit, so the change won't make it any worse.

Pahole example:

• Comment /* XXX {n} bytes hole, try to pack */ shows where optimization is possible by rearranging the order of fields structures and classes

Master branch

struct ScreenManager_ {
        int                        x1;                   /*     0     4 */
        int                        y1;                   /*     4     4 */
        int                        x2;                   /*     8     4 */
        int                        y2;                   /*    12     4 */
        Vector *                   panels;               /*    16     8 */
        const char  *              name;                 /*    24     8 */
        int                        panelCount;           /*    32     4 */

        /* XXX 4 bytes hole, try to pack */

        Header *                   header;               /*    40     8 */
        Machine *                  host;                 /*    48     8 */
        State *                    state;                /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */
        _Bool                      allowFocusChange;     /*    64     1 */

        /* size: 72, cachelines: 2, members: 11 */
        /* sum members: 61, holes: 1, sum holes: 4 */
        /* padding: 7 */
        /* last cacheline: 8 bytes */
};

This PR

struct ScreenManager_ {
        int                        x1;                   /*     0     4 */
        int                        y1;                   /*     4     4 */
        int                        x2;                   /*     8     4 */
        int                        y2;                   /*    12     4 */
        _Bool                      allowFocusChange;     /*    16     1 */

        /* XXX 3 bytes hole, try to pack */

        int                        panelCount;           /*    20     4 */
        Vector *                   panels;               /*    24     8 */
        const char  *              name;                 /*    32     8 */
        Header *                   header;               /*    40     8 */
        Machine *                  host;                 /*    48     8 */
        State *                    state;                /*    56     8 */

        /* size: 64, cachelines: 1, members: 11 */
        /* sum members: 61, holes: 1, sum holes: 3 */
};

Info about technique:

https://hpc.rz.rptu.de/Tutorials/AVX/alignment.shtml

https://wr.informatik.uni-hamburg.de/_media/teaching/wintersemester_2013_2014/epc-14-haase-svenhendrik-alignmentinc-presentation.pdf

https://en.wikipedia.org/wiki/Data_structure_alignment

https://stackoverflow.com/a/20882083

https://zijishi.xyz/post/optimization-technique/learning-to-use-data-alignment/

Affected structs:

• ScreenManager 72 to 64 bytes
• Screen/DynamicIterator 24 to 16 bytes
• Meter/DynamicIterator 24 to 16 bytes
• IncMode 152 to 144 bytes
• TraceScreen 64 to 56 bytes
• LinuxProcessTable 120 to 112 bytes
• FunctionBar 40 to 32 bytes

[GermanAizek]

Fixed merge conflicts.

[BenBE]

Please use rebase to update your PR. TIA.

Also note the comment regarding the ordering of struct TraceScreen_.

[fasterit]

@GermanAizek can you please rebase and fix the comment as per above before we change more? Otherwise your PR will age (too) fast.
Thanks /DLange

[fasterit]

In file included from DisplayOptionsPanel.h:10,
from DisplayOptionsPanel.c:10:
FunctionBar.h:14:4: error: unknown type name ‘uint32_t’
14 | uint32_t size;
| ^~~~~~~~
In file included from InfoScreen.h:13,
from CommandScreen.h:11,
from CommandScreen.c:11:
FunctionBar.h:14:4: error: unknown type name ‘uint32_t’
14 | uint32_t size;
| ^~~~~~~~

--> missing #include <stdint.h>, fixing this